'Ai> BOTCHT FROM I ii .. --- ^^ LIBRARY \ PSYCHOLOGY. Reviews of the First Edition. PSYCHOLOGY. " We regard Father Maher's book on Psychology as one of the most important contributions to philosophical literature published in this country for a long time. . . . What renders his work especially valuable is the breadth of his modern reading, and the skill with which he presses things new, no less than old, into the service of his argument. His dialectical skill is as remarkable as his wealth of learning, and not less notable is his spirit of fairness. . . . W' hether the reader agrees or disagrees with the author's views, it is impos- sible to deny the ability, fulness, and cogency of the argument." — St. James's Gazette, July 8, 1892. "... The author has proved himself a thoroughly competent guide and teacher on the subject of his work. Almost every page of his book bears the mark of careful thought and wide reading. . . Taken for what it professes to be, this is an e.Kcellent manual. It deserves and will repay study," — The Scotsman, August 4, 1890. " This book, by the Professor of Mental Philosophy at Stony- hurst College, is a sober, scholarly, and important work. . . . The author's treatment of Psychology is simple, logical, and .graceful. His definitions are clear and precise, his style is crisp and nervous, and his knowledge of the literature of his subject is very consider- able." — Educational Review, June, 1S91. "This Manual is an able and well-considered effort to reconcile mediaeval and modern philosophy. The author bases his argument mainly on the works of Aquinas and the schoolmen, but he gives fair recognition to modern philosophers and to modern science. . . . We can commend the book to students of Natural Theology and Psychology." — The Church Review, September 26, 1890. "Father Maher's joining of old with new in his Psychology is very skilful ; and sometimes the highly systematized character of the scholastic doctrine gives him a certain advantage in the face of modern psychological classifications with their more tentative character. . . . The historical and controversial parts all through the volume are in general very careful and well managed." — Mind. " The author is always lucid, cogent, and learned. His know- ledge of the works of writers on Psychology is thorough and sound, and results in a most valuable aid to the student : particularly good examples of this are his historical sketches of the Theories of External Perception, General Cognition, and the Moral Sense, whilst the historical references and notes on almost every point should prove extremely helpful."— T//^ University Correspondent, November, 1890. "This work cannot be too highly recommended." — The Tablet^ November i, 1890. ". . . The book is a distinct gain to psychological science, and places its author in the front rank of the clear, deep thinkers of our time. It is a thoroughly scientific work, evincing on the part of its author great powers of analysis and discrimination, with the most profound and varied knowledge of philosophical literature." — The Irish Ecclesiastical Record, January, 1891. STONYHURST PHILOSOPHICAL SERIES. ^PSYCHOLOGY: EMPIRICAL AND RATIONAL. }^^ %.^^^ BY p. MICHAEL MAKER, S.J., I ; D. LIT., M.A. LOXD. PROFESSOR OF MENTAL PHILOSOPHY AT STONYHURST COLLEGE, EXAMINER FOR THE DIPLOMA IN TEACHING OF THE ROYAL UNIVERSl'lY OF IRELAND. FIFTH EDITION. (eleventh to thirteenth thousand.) LONGMANS, GREEN, & CO 39 PATERNOSTER ROW, LONDON, NEW YORK AND BOMBAY igo2 Fir? ROEHAMPTOX '. PRINTED BY JOHN GRIFFIN. C/ 1>^ ^ EDUC. PSYCH. LI8RARy PREFACE TO FOURTH EDITION. The unhoped for success which met the present Avork in the form in which it was printed in i8go induced me to abstain from making more than a few verbal changes in the second or third editions. But by the time the fourth edition of the book was called for the large quantity of fresh psychological literature which had appeared, especially from America, in the entire interval, had rendered sundry additions and alterations desirable. The process of emendation once begun it was not easy to draw the line, and the result is that the present volume is practically a new work containing a considerably larger quantity of matter than the former. The limitations of the series have forced me to squeeze many topics into small type, as I was unwilling to omit them altogether. The unexpectedly extended circulation has, however, made publication possible without a corresponding augmentation of the price. The modifications up to the ninth chapter are, with the exception of the enlarged treatment of physiology, psycho-physics, and psychometry com- paratively slight ; but thenceforward the book has been virtually re-written. Chapters xiv., xvi., 1()931() vi PREFACE. xvii., xviii., xix., xxii., xxiv., are, minus occasional sections, new : the Supplement on Hypnotism and the criticisms of the theories of Professors James and Hoffding entire!}' so. The historical sketches — which I believe have proved helpful to various classes- of students — have also been substantially increased, and I trust considerably improved. I have alsa introduced a number of diagrams which illustrate the brain and nervous system. My aim here, as in the previous editions, has been not to construct a new original S3'Stem of my own, but to resuscitate and make better known to English readers a Psychology that has already sur- vived four and twenty centuries, that has had more influence on human thought and human language than all other psychologies together, and that still conmiands a far larger number of adherents than any rival doctrine. My desire, however, has beert not merely to expound but to expand this old system ; not merely to defend its assured truths^ but to test its principles, to develop them, to apply them to the solution of modern problems ; and to- re-interpret its generalizations in the light of the most recent researches. I have striven to make clear to the student of modern thought that this ancient psychology is not quite so absurd, nor these old thinkers quite so foolish, as the current carica- tures of their teaching would lead one to imagine ; and I believe I have shown that not a little of what is supposed to be new has been anticipated, and that most of what is true can be assimilated without much difficulty by the old system. On the other PREFACE. vn hand, I have sought to bring the scholastic student into closer contact with modern questions ; and to acquaint him better with some of the merits of modern psychological analysis and explanation. There is at least one phase of current psycho- logical literature to which my opposition is in no way diminished — the prevalent view that the science of psychology and ihe philosophy of the human mind can be shut up in water-tight compartments and rendered completely independent of each other. Indeed, the now customary vehement protestations of psychologists that their works are innocent of all philosophical beliefs — if not also devoid of all metaphysical foundations — and the austere gravity with which they are wont to apologize whenever they make mention of the soul, or allude to such irrelevant matters as the possibility of a future life, the origin of the human mind, or its connection with the body, have often appeared to me liable to give rise to the suspicion that the sense of humour is incompatible with psychological eminence. For it is now taken for granted by the most distinguished of these writers that of all human beings the student of psychology feels least interest in the question as to whether he has a soul, or what is to become of it ; and that of all branches of human knowledge the science of the mind has least to say on such a topic. In fact, to trespass in such alien matters is universally assumed to be the gravest of professional delinquencies. Notwithstanding the weight of authority for this view, I have had the temerity to suggest that it is viii PREFACE. the most misleading and extravagant idolon of the psychological cave at the present day. I have even ventured to maintain throughout this work that to construct such a water-tight science of psychology, from which all metaphysical conceptions and beliefs have been effectually bailed out, is simply impossible. Accordingly, I warn my readers at the start that the analysis of mental activities which commends itself to me as the truest and most thorough, has resulted in the conception of the human mind as an immaterial being endowed with free-will and rational activity of a spiritual order ; and that my exposition and interpretation of the phenomena lead back to this conclusion. At the same time my procedure throughout is purely rationalistic, in the sense of being based solely on experience and reasoning. There seems to have arisen in some minds the notion that the works of this series assume or imply dogmatic beliefs pertaining exclusively to revealed religion. Of course no one who had read my volume, or who was at all familiar with the series, could have fallen into such an error; but it may be as well to repeat formally here that this work is purely philosophical, and that it contains nothing to which, not merely every Christian, but every Theist may not assent. Indeed, the very first insti- tution to adopt this work as a text-book, save that in which I am engaged in teaching, was a Protestant Theological College in the South of England. I have profited much by the various criticisms and reviews of the first edition, which were uniformly PREFACE. ix very friendl}^ even when the writers were widely opposed to my philosophical views. But in spite of the very large alterations and, I trust, improve- inents in form of treatment, there is no change of importance in doctrine in the present work. I wish here, to make general acknowledgment also of my indebtedness to many writers of various schools — foes no less than friends. I have endea- voured throughout the volume to indicate the particular sources from which I have derived special assistance ; and I have been all the more careful in this matter, as I have observed that some writers have shown a very practical appreciation of my own labours, without obtruding the fact upon their readers. In addition, I desire to express my obligations to the Rev. H. Irwin, S.J., for sundry valuable suggestions, and also for having corrected all the proofs. A few hints on judicious skipping may be useful. I have marked with special headings the more scholastic and metaphysical discussions. The student, unless he be already familiar with or specially interested in the philosophy of the schools, had better omit these on first reading. The beginner will similarly find a flanking movement preferable to a frontal attack with respect to the longer historical sketches. For the general reader perhaps the most interesting course would be to start with chapter xix. on Free-will, then to read from chapter xxi. to the end of the volume, after which he may begin the book and follow his own tastes. The portions of Psychology generally PREFACE. deemed of most importance from the standpoint of the theory of Education are dealt with in the following sections: pp. i — 21, 26 — 51, 59—92, 125 — 152, 163 — 200, 208—241, 292 — 303, 314 — 326, 344—367, 37^—?>9^, 424—448, 454— 45S. The relevanc3% however, of these topics to the art of teaching varies much, as the intelligent reader will perceive for himself. On the other hand, for the benefit of the more advanced or more earnest student, I have indicated a considerable quantity of useful supplementary reading on very many questions of interest which the limits of my space have compelled me to treat more briefly than I desired. All the French works cited can be obtained, I believe, through Alcan (Paris), the German through Herder (Freiburg). Stonyhurst, October, 1900. PREFACE TO FIFTH EDITION. The fourth edition of the present work, con- taining 3,000 copies, having been exhausted in two years, the Fifth Edition, which has been carefully revised, is now issued. Sundry verbal changes and corrections have been introduced, and the section on the muscular sense has been re-written, but the chief addition is a Supplement containing a reply to Mr. Mallock's criticism. Stonyhurst, October, 1902. TABLE OF CONTENTS, Illustrations Pp- ^^^ — ^^^^ INTRODUCTION. CHAPTER I. Definition and Scope of Psychology . . . Pp. i— lo Definitions of Psychology, Subjective and Objective, i, seq. —Scope, 2— Empirical and Rational Psychology, 5— Psychology distinguished from Cosmology, 6— From Logic, 7— From Ethics, 8 — Relations with Physiology, 9. CHAPTER II. Method of Psychology Pp- n — 25 Psychology a Science, 11— Introspective Method, 11 — Objec- / tive or Supplementary Methods, 13— These Methods not new, 18 \^ —Rational Psychology deductive, 18— Attacks on Psychology, 19 — Objections to Introspection answered, 20 — Real difticulties, 24. CHAPTER III. Classification of Mental Faculties . . . Pp. 26—41 Consciousness, 26 — Subconscious mental activities, 27 — Mental Faculties classified, 28— Subdivision, 32— Various classifications : 1/ Aristotle's, 33— St. Thomas', 33— Scotch school, 34— Hamilton's, 34 Herbert Spencer's, 35— Attacks on Mental Faculties, 36— Mutual relations of the Faculties, 39 — Feeling, 40. BOOK I. Empirical or Phenomenal Psychology. Part I. — Sensuous Life. CHAPTER IV. Sensation . • Pp- 42 — ^^ Sensation, Sense and Sense-organ defined, 42— Excitation of Sensation, 43— The Nervous System, 44— Properties of Sensation, Quality, Intensity, Duration, 46— Composite stimuli, 47— Cognitive Character of Sensation, 48— Sensation and Perception, 49— Scho- lastic doctrine of sfccies, 51— Experimental Psychology ; Psycho- physics, 54— Interpretations of the Weber-Fechner Law, 58 — Psychometry : Reaction-time, 59. xii CONTENTS. CHAPTER V. The Senses Tp. 63—97 How many External Senses, 63 — Taste, 65 — Smell, 66 — Touch, 68 — Organic Sensations, Common-sensibility, Coenaesthesis, or the Vital Sense, 69 — Sense of Temperature, 70— Contact or Passive Touch, 71 — Cognitional value of Touch, 72 — Active Touch, Muscu- lar Sensations, 74 — Hearing, 79 — Sight, 83 — The Senses compared, 58— The " Law of Relativity," 90 — Scholastic doctrine of the Internal senses, 92 — Internal sense, 95 — Common sense, 96. CHAPTER VI. Perception of the Material World : Critical Sketch of the leading theories of External Perception .... Pp. 98 — 124 Psychology and Philosophy of Perception, 98— Sceptical Theories, 99 — Philosophical proof of Realism, 100 — Psychology of Perception, loi — Ambiguity of Terms, 104 — Ego and Mind, 104 — Two Questions, 105 — Historical sketch : Descartes, Locke, Berkeley, 108 — Hume, Mill, and Bain, no — Kant, 117 — Herbert Spencer, 122. CHAPTER VII. Development of Sense-Perception. Education OF THE Senses Pp. 125 — 162 Growth of Knowledge, 125 — Complexity of perceptional process, 126 — Development of Tactual Perception, 127— Tactual cognition of the Organism, 130 — Of other Objects, 132 — Cognition of other Minds, 133 — Secondary acquisitions, 134 — Visual Perception, 135 — Immediate Perception of Surface Extension, 137 — Mediate Percep- tion of Distance and Magnitude, 139 — Binocular Vision, 142 — Erect Vision, 144 — Auditory Perception, 145 — Gustatory and Olfactory Perception, 146 — Objections solved, 147 — Co-operation of Faculties, 147 — Intelligent Cognition not mere Instinctive Belief, 149 — Mental nd Cerebral Development, 150 — Primary and Secondary Qualities of Matter, 152 — Views of Aristotle. St. Thomas, 153 — Descartes, Locke, Berkeley, Hume, 154 — Hamilton, Spencer, 155 — The Rela- tivity of Knowledge, 157. CHAPTER VIII. Imagination ........ Pp. 163 — 178 Imagination compared with Perception, 1G3 — Productive and Reproductive, 165 — yEsthetic, 166 — Scientific, 167 — Dangers of, 170 — Fancy, Wit, Humour, 170 — Illusions, 171 — Dreaming, 176. CHAPTER IX. Memory. Mental Association .... Pp. 179 — 207 Memory defined, 179 — Reproduction and Recollection, 180 — Laws of Association, 181 —Reduction of those laws, 1S4 — Physio- logical hypothesis, 18S — Co-operative and Contiicting Associations, CONTENTS. xiii i88 — Secondary Laws, igo— Retention, igi — Ultra-spiritualist theory, 192 — Purely physical theory, 194 — Recognition, 195 — Remi- niscence, ig6 — Intellectual and sensuous memory, 197 — Scholastic controversy, 198 — Qualities of good memory, 199 — Training of Memory, 200 — Historical sketch of the doctrine of mental associa^^ lion: Aristotle, St. Thomas, 201 — Locke, Hobbes, Hume, Hartley,/ 203 — James Mill, 204— J. S. Mill, Bain, Sully, 205 — Obliviscence, 206.J CHAPTER X. Sensuous Appetite and Movement .... 208 — 220 Sensuous Appetency, 20S — Scholastic doctrine of Appetency, 208 — IMovement, 210 — Voluntary movement analyzed, 210 — Auto- matic, Reflex, Impulsive, 211 — Origin of voluntary movement: Theory of random action, 212 — Theory of instinctive action, 213 — Growth of control of movement : Probable theory, 214 — Movements classified: Secondary-automatic and Ideo-motor action, 218. CHAPTER XI. Feelings of Pleasure and Pain .... Pp. 221 — 228 Feeling and other terms defined, 221 — Aristotle's Theory of Feeling, 222 — Laws of Pleasure and Pain, 225 — Feeling not a third Faculty, 226 — Theories of Pleasure and Pain, 226. BOOK I. {continued.) Part II. — Rational Life. CHAPTER XII. Intellect and Sense Pp. 229 — 251 Erroneous views, 229 — Sensationalism, Materialism, Pheno- menism, Positivism, Associationism, Evolutionism, 230 — Intellect essentially difterent from Sense, 230 — Proved by Attention, 232 — Comparison and Judgment, 233 — Necessary Judgments, 234 — Universal and Abstract Concepts, 235 — Reflection and Self-con- sciousness, 238— Intellect a spiritual faculty, 239 — Intellect medi- ately dependent on the Brain, 241 — Balmez on Sensationism, 242 — Lotze, 245 — Controversy concerning Universals : Extreme Realism, 247 — Nominalism, Conceptualism, 248 — Moderate Realism, 249. CHAPTER XIII. Conception. Origin of Intellectual Ideas. Erroneous Theories Pp. 252 — 291 Origin of Ideas, 252 — Theory of Innate Ideas, 253 — Empiri- cism, 254— Historical sketch of Theories of General Knowledge : Plato, 255— Descartes, 256— Geulincx, Malebranche, 258— Spinoza, 260— Leibnitz, 262 — Rosmini, 264 — Kant, 265 — J. G. Fichte, 270 — Locke, 270 — Bain, 272 — Sully, 275 — Comte, 279 — Origin of Neces- sary Truths: Associationism, 281 — Evolutionist Theory, 286— Intuitionalist Doctrine, 289. xiv CONTENTS. CHAPTER XIV. •CoN'CEPTiON. Origin of Intellectual Ideas {continued) Pp. 292 — 313 Thought an Activity, 292 — Thought Universal, 293 — Concep- tion : Two questions, 293 — Elaboration of Universal Concepts, 294 — Intellectual Apprehension, 297 — Comparative Abstraction, 297 — •Comparison and Discrimination, 29S — Generalization, 299 — Thought and Language, 302 — Second Question : Origin of Ideas, 302 — Aristo- telico-scholastic Theory of Abstraction, 305 — Doctrine of St. Thomas, 312. CHAPTER XV. Judgment and Reasoning ..... Pp. 314 — 344 Judgment defined, 314 — Analysis of judicial process, 315 — Assent and Consent, 318 — Reasoning defined, 320 — Analysis of Ratiocination, 320 — Deduction and Induction, 321 — Implicit reason- ing, 322 — The Logic of real life : Newman's Grammar of Assent, 324 — Thought viewed differently by Psychology and Logic, 325 — Belief: Historical sketch, 326 — Three questions: (A) Nature of Belief, 328 — Belief and Knowledge, 329 — (B) Causes of Belief, 331 — (C) Effects, 334 — Conscience, 334 — Scholastic view, 335 — Other Theories : Moral Sense, 336 — Associationist theory, 337 — Origin and Authority of moral judgments, 339 — Evolutionist hypothesis, 340 — Intuitionalism, 342 — Kant, 342 — Conscience a Spring of Action, 342 — Butler's doctrine, 343. CHAPTER XVI. Attention and Apperception .... Pp. 345 — 360 Attention and Sensation, 345 — Attention and Volition, 346 — Attention interrogative, 346 — Voluntary and non-Voluntary Atten- tion, 347 — Laws of Attention, 348 — Effects, 349^Attention and Genius, 351 — Physiological conditions, 352 — Pleasure and Pain, 353 — Education, 354 — -Unconscious modifications of the Mind, 355 — Apperception, 357 — Historical sketch, 358— Nature of Apperception, 359 — Apperception and Education, 360. CHAPTER XVII. Development of intellectual cognition : Self AND other important IDEAS . . . Pp. 36I— 377 Reflexion : Grades of Consciousness, 361 — Growth of the Knowledge of Self, 362 — ^The developed Mind's consciousness of itself, 363 — Abstract Concept of Self, 365 — Unity, Continuity, Dis- continuity of Consciousness, 366 — Genesis of other Ideas, 367 — Substance, Accident, Cause, 368 — The Infinite, 370— Space, 371 — Cognition of Time, 372— Development of this Idea, 373— Subjective .and Objective Time, 374 — Relativity of our appreciation of Time, 375 — Localization in Time, 375— Expectation, 376. CONTENTS. XV CHAPTER XVIII. Rational Appetency Pp. 378—393 Rational Appetency: Desire defined and analyzed, 378 — Is Pleasure the only object of Desire, 379— Motive, 3S0— Spontaneous action and Deliberation, 381— Choice or Decision, 382— Volition, Desire, and various forms of conative activity, 384 — Self-control, 385— Order of development, 388— Habit : Practical rules, 388; Moral discipline, 390— Character, 392— Temperaments, 393. CHAPTER XIX. Free-Will and Determinism .... Pp. 394—424 Free-Will : Philosophy and Psychology, 394— Free-will defined : Scholastic terminology, 395 — Problem stated, 396— Fatalism and Determinism, 397 — Argument from Ethical Notions: Obligation, 39S— Merit and Desert, 401— Responsibility, 402— Justice, 404— Free-will and Ethics, 405— Argument from Consciousness: Atten- tion, 406— Dehberation, 408 — Decision or Choice, 409— Adhesion to resolution, 411— Metaphysical argument, 413— Objections : Psycho- logical, 415— Metaphysical, 419— From Science, 420— Theological, CHAPTER XX. The Emotions. Emotional and Rational Language '• .Pp. 425—458 Feeling and Emotions, 425— Scholastic view, 426— Chief forms of Emotion, 427— Self-regarding, 427— Altruistic, 430— Attached to intellectual activity, 432— iEsthetic, 435— The Moral Sentiments, 440— No distinct Faculty of feeling, 442— Genesis of Feelings : James's theory, 443— Classification of Emotions, 446— Expression of Emotions, 449— Evolutionist Theory, 450— Origin of Language, 454. BOOK II. Rational Psychology. CHAPTER XXI. Substantiality, Identity, Simplicity, and Spiritu- ality OF the Human Soul . . . Pp. 459—473 Scope of Rational Psychology, 459— Its importance : Method, 460— SubstantiaUty of the Soul, 461— Validity of Notion of Sub- stance, 462— The Mind is a Substantial Principle, 463— Abiding Identity of the Mind, 464— Simplicity, 466— Spirituality, 469. CHAPTER XXII. False Theories of the Ego .... Pp. 474 — 492 Kant's Theory, 474— Empiricist theory: Hume, 475— Mill, 476 — W. James's theory, 477— James's Attack on the Soul. 4S1— Double Consciousness and "Alterations of Personality," 487— Criticism, 489. XVI CONTENTS. CHAPTER XXIII. Monistic Theories . . . . . . . Pp. 493 — 524 Dualism and Monism, 493 — Spiritualist Monism or Idealism. 494 — Materialism, 495 — Thought is not a secretion of the Brain, ^gg—Nor a function, 497 — Nor a resultant of material forces, 497 — Dependence of Mind on Body, 499 — Shadworth Hodgson's "Con- scious Automaton," theory 503 — New-Spinozism, Double-Aspect theory, or Identity-hypothesis, 505 — Mind-stuff: Clifford, 506 — Bain, 507 — Spencer, 508 — Mental States not composite, 510 — Incredible consequences, 513 — Monism: Conservation of Energy: Hoffding's doctrine, 517— Criticism, 520— Law of I nertia, 523 — Agnosticism, 524. """^ " CHAPTER XXIV. Immortality of the Soul ..... Pp. 525—544 Immortality and Psychology : Theism, 525 — Teleological Argu- ment, 526— P:thical Argument, 529— Formal Theistic proof, 533— Argument from Universal belief, 533 — Scholastic Ontological Argu- ment, 5^^ — Objections against the doctrine of a Future Life, 537. CHAPTER XXV. Soul and Body Pp. 545—561 Individuality of the Human Soul, 544 — Unicity of the Soul in man, 545 — Vitalism and Animism, 546— Organicism : Physico- chemical theories of Life inadequate, 547 — Definitions of Life, 551 — Union of Soul and Body : Ultra-dualistic theories, 553 — Aristo- telico-scholastic doctrine, 555— Soul and Body one Nature and Person, 558 — Aristotle's definition of the Soul, 560. CHAPTER XXVI. Soul and Body {continued). Other Problems . Pp. 562 — 578 Locus of the Soul, 562 — The Soul present throughout the Body, ^5^ — Phrenology, 564 — Localization of Cerebral P^unctions, 565 — Methods of research, 566— D. Ferrier, Plechsig, 567 — Origin of the Soul, 572 — Traducianism and Creation, 574 — Time of its Origin : Scholastic doctrine, 575 — Lotze and Ladd, 576 — Origin of the first Human Soul : Evolution Theory, 578. SUPPLEMENTS. A. — Animal Psychology Pp. 579—594 Comparative Psychology, 579 — Difficulties of Animal Psycho- logy, 580 — Cartesian Theory : Animals sentient, 582 — Animals irrational, 583— Instinct, 5S7 — Origin of Instinct : Evolutionist Theories, 588— Animal " Souls," 593. B. — Hypnotism Pp. 594 — 601 Hypnotism : Historical sketch, 594 — Induction and Character- istics of hypnotic state, 595 — Theories concerning Hypnotism, 598 C.— Repj^y to Mr. Mallock's Criticism . Pp. C03— Cio DIAGRAMS ILLUSTRATING THE STRUCTURE OF THE NERVOUS SYSTEM DESCRIBED' IN THE TEXT. For the subject-matter of Figures I. — III. see pp. 44 — 46- Fig. I. — Side view of Brain and Spinal Cord. (Barnet.) CEREBRUM MEDULLA OBLONGATA J 3EREBELLUM 'INAL CORD Fig. II.— Spinal Cord and Nerves, with Sympathetic Chain on one side. SPINAL COLUMK CUT ENDS OF SPINAL NERVEa Fig. III.— Roots of a Spinal Nerve issuing from the Cord : viewed (A) from before ; (B) from the side; (C) from above; (D) the ^ roots separated. s^^ ^.^'* <>v alO ■>>■% A\ \', pons varolii, below which is the medulla oblongata; C i to 8, the cervical nerves ; a to x, , anterior fissure ; 2, posterior fissure ; 3 and 4, lateral the sympathetic chain grooves of cord ; 5, anterior, efferent, or motor root ; connected with spinal 6, posterior, afferent, or sensory root. (Furneau.x. ) nerves. (Furneau.x.) FRONT REAR Fig. IV. — The Human Brain. A, cerebrum ; b, cerebellum c, pons varolii ; D, medulk oblongata ; e, fissure o Silvius. 1 1 I Fig.V. — Under surface ct Brain, showing origi of the twelve pairs ( cranial nerves. I, great longitudinal fissur« 2, 2' 2", convolutions of ba of cerebrum, frontal lobe; 3, base of fissure of Silviui 4, 4', 4", bases of cerebrur temporal lobes ; 5, 5', oc< pital lobes ; 7, 8, 9, 10, cat bellum ; 6, medulla oblo gata; I. — IX. .cranial nerv« VI. VII. on pons varc indicate roots of ocular a: facial nerves. (Bastian.) (See Text, pp. 44—4'^)- Th 1 ig. VI. — Upper surface of Brain, arachnoid membrane being- removed. (Gray.) LOWER FROMTAL FISSURE ROL.ANDO PARIETO-OCCIPITAL FISSURE REAR This illustration shows the chief convolutions and fissures of the cerebrum from above. The two hemispheres are divided by the great longitudinal or median fissure. (See Text, pp. 45, 567—570). o o -< H* ^ ca S3 B 12. O P Ui ^ OJ o o P en M r-^ g O < o -1 P 3 r^ P 3 p 3 3 o 5 2 o 2 O fD 3 •-1 p o p g' 3 o 3 a t/: g r^ cr '" r^ «j p • hJ t/1 " M __d r^ g rv P m' y o <_ to " FT rt c' ~ C^ r^ o 5- ffq re o ir.' o' 3 .J o o' vp M O t/) C/l g 5 On rD P -i p 3 rT o o o 2 J7 < H 4- o ,*"!' C OD g' O Crq (/> a" to c PSYCHOLOGY. > > > I Introduction. CHAPTER I. DEFINITION AND SCOPE OF PSYCHOLOGY. Definition. — Psychology (r?}? -^vxv^ X0709) is that branch of philosophy which studies the human mind or soul. By the mind or soul (yfruxv) is meant the thinking principle, that by which I feel, know, and will, and by which my body is animated. The terms Ego, Self, Spirit, are used as synonymous with mind and soul, and, though slight differences attach to some of them, it will be convenient for us (except where we specially call attention to diver- gencies of meaning) to follow common usage and employ them as practically equivalent. Subjective and Objective. — In modern philo- sophy the mind is also called the Subject, especially when set in contrast with the external world, which is characterized as the Object. The adjective sub- jective is similarly opposed to objective, as denoting mental in opposition to extra-mental facts, what pertains to the knowing mind as contrasted with B PSYCHOLOGY. what belongs to the object known. Thus a train of thought, an emotion, and a dream are said to be subjective ; whilst a horse, an election, and a war are objective realities. Such are the primary signi- fications of these terms, but the meanings vary with different writers.^ An objection. — We may here be met with the objection that wc are unwarrantably postulating at the very commencement of our work the most disputed doctrine in the whole science of Ps3^cho- logy — the existence of some '* inscrutable entity," called the soul. To this we reply that for the present we only use the term provisionally to indi- cate the source or root of our conscious states. We make no assumption as regards the nature of this principle. Whether it be the brain, the nervous system, the whole organism, or a pure spirit, we do not yet attempt to decide. But we claim to be justified, in employing the familiar terms soul and mind to designate this apparent bond, by the obvious fact that our various mental states manifest them- selves as bound together in a single unity. Scope of Psychology. — The subject-matter of our science is, then, the Soul or Mind. The psycho- logist investigates those phenomena which we call sensations, perceptions, thoughts, volitions, and emotions; he analyzes them, classifies them, and ^ In strict language the vv'ord miud designates the animating principle as the subject of consciousness, while soul refers to it as the root of all forms of vital activity. Spirit is of still narrower extension than mind, indicating properly a being capable of the higher, rational, or intellectual order of conscious life. E<^o and self strictly signify the whole person constituted of soul and body. DEFINITION AND SCOPE. seeks to reduce them to the smallest number of fundamental activities. He studies the nature of their exercise and the laws which govern their operations, and he endeavours to enunciate a body of general truths which will accurately describe their chief and most characteristic features. But Psychology cannot rest here. Whether it wishes it or not, Psychology is inevitably a branch of Philo- sophy.^ It cannot remain satisfied with the mere generalization of facts; it must pass on to inquire into the inner nature and constitution of the root and subject of these phenomena; it must seek to explain the effect by its cause. Consequently, a work which does nothing more than describe and classify the operations of the mind, omitting all discussion regarding the mind itself, is but an abortive attempt at a science of Psychology,^ La " Etymologically, Philosophy {vy^) ; the faculty of Sensuous Percep- tion {to aia9r)TLK6v), by which the objects perceptible by sense are represented in our cognition, the Locomotive Faculty {to KLvrjTtKov), by which we are enabled to move the body and its members, and make use of them for external action; and lastly, the Reason (to Stavor^TiKoV). The four faculties first-named belong to brutes, as v\^ell as to man. Reason, on the other hand, is the charac- teristic which distinguishes man from the brutes."^ Scholastic System.— St. Thomas follows Aristotle,'^ but 5 Stockl's Handbook of the History of Philosophy (Translated by Thomas Finlay, S.J.), p. 119. This work contains an excellent epitome of Aristotle's Philosophy. ^ Cf. Sum. i. q. 7S. a. 10. D 34 PSYCHOLOGY. lays greater stress than the Greek philosopher on the distinction between mere sensitive appetite (opcit? aXoyos), for which we are not responsible, and rational appetite or will." Leaving out of account, then, the physiological or extra mental powers of the soul, we have cognitive capabilities of the sensuous order ; intellect, or the faculty of rational knowledge; and the two kinds of appetite. This is the scheme which we have ourselves adopted. With St. Thomas, as with us, emotional states are either complex products made up of cognitive and appetitive activities, or mere aspects of such energies. Scotch School. — Among modern writers, Reid and Stewart put forward the distribution into Intellectual and Active Powers, based on the antithesis maintained by the peripatetics between the cognitive and appetitive faculties. In doing so, however, they overlooked the equally important principle of division into Sensuous and Rational aptitudes, all forms of cognition bemg alike styled intellectual. In addition to this deficiency, their classification errs b}' opposing intellectual to active, whereas the higher order of cognitive activity is as essentiallv active as many modes of appetency. Tripartite Division. — Hamilton adopts the three-fold distribution of the facts of consciousness into pheno- mena of Knowledge, of Feeling, and of Conation. This classification, first propounded last century by Tetens, a German philosopher, was popularized by Kant, and probably enjoys most general favour among psycho- logists of the present day. It bases its claims on the assumption of three ultimate radically distinct modes of conscious activity to one or other of which all forms of mental life are reducible, while none of these, it is asserted, can be identified with, or resolved into, either of the other two. Consciousness assures me, it is urged, that I am capable of Knowledge, of seeing, hearing, imagining, reasoning, and the rest. It also testifies to the fact that I may be drawn towards or repelled from objects, in other words, that I am endowed with the faculty of Desire. Finally, it reveals to me that I ' Sum i. q. 80. a. 2. CLASSIFICATION OF THE MENTAL FACULTIES. 35 experience pleasure and pain, and that I am subject to various emotions, such as curiosity, pride, anger, and admiration, which are not acts of cognition, nor yet of desire. Accordingly there must be postulated as the basis of this last class of states a third capability in the mind, the Faculty of Feeling. Our objection to this scheme is that it sins both by excess and defect. On the one hand it ignores the fundamental distinction between the lower and higher grades of mental life, and on the other hand it asserts without sufficient grounds the existence of a separate third faculty. Hamilton, like most Kantians, was at times fully aware of the divergence in kind which marks off rational from sensuous cognition. Yet this all-important difference receives no real recognition in his classification, whilst the phenomena of feeling, for which he demands a third compartment, are reducible either to aspects of cogni- tive energies or modes of appetency. Spencer's Bipartite Division. — Mr. Herbert Spencer rejects the triple division of mental phenomena for a two-fold one: (i) Feelings, and (2) Relations between Feelings or Cognitions. In his view volition is merely a complex form of feeling, and even the " relations " between feelings he speaks of as being merely special feelings. As a psychological classification this division has been very justly, but not consistently, rejected by Dr. Bain, on the ground that what is required is not a scheme of mental products, but of the different kinds of powers or forces of the mind by which such products are attained.^ Looked at, however, as an ultimate analysis of our mental operations, it must be condemned as proceeding from a false conception of mental life.'\ ^ The Senses and Intellect, p. 640. (2nd Edit.) 9 H. Spencer, Bain, Mr. Sully, and all empiricists, since they teach that the mind is nothing more than the sum of our conscious states, mean by a faculty merely a group of like mental acts, while Hamilton, who believes that the mind is a real indivisible energy, conceives the different faculties, not, indeed, as independent agents, but as special forms of causahty or susceptibility in the soul. 36 PSYCHOLOGY. Attacks on Mental Faculties. — But difference of view on the subject of the mental powers has not been confined to the problem of classification. A vigorous crusade has been preached by several psychologists during the present century against the "faculty hypothesis" in any form. The move- ment was initiated in Germany by Herbart in opposition to Kant, and has been sustained there by Drobisch, Beneke, Schleiermacher, Vorliinder, and others. In France, MM. Taine, Kibot, and positivists generally, have followed in the same direction, and a vast amount of wit and rhetoric has been expended in the demolition of these " metaphysical phantoms." We believe, nevertheless, that, once the reality of the mind as a permanent indivisible energy is admitted, the assumption of faculties when properly explained is unassailable. Faculty defined. — A mental faculty or power is not of the nature of a particular part of the soul, or of a member different from it as a limb is distinct from the rest of the body. It is not an independent reality, a separate agent, which originates conscious states out of itself apart from the mind. But neither is it merely a group of con- scious states of a particular kind. It is simply a special mode through which the mind itself acts. " It is admitted by all that a faculty is not a force distinct from and independent of the essence of the soul, but it is the soul itself, which operates in and through the faculty." ^"^ A faculty is, in fact, the proximate ground of some special form of activity of which the mind is capable. That we are justified in attributing to the soul faculties in this sense is abundantly clear. Careful use of our power of introspection reveals to us a number of modes of psychical energy radically distinct from each other, and incapable of further analysis. To see, to hear, to remember, to desire, are essentially different kinds of consciousness, though all proceed from the same source. Sometimes one is in action, sometimes another, but no one of them ever exhausts the total energy of the mind. They are partial utterances of the same indivisible subject. But this is equivalent to the establishment of certain distinct aptitudes in the mind.^^ ^" Cf Die PsycJioIogie, von Dr. Constantin Gutberlet, p. 4. ^' " The proposition, ' our soul possesses different faculties,' means nothing else than ' our soul is a substance which as active principle is capable of exerting different species of energies.' " " If the soul produces within itself acts of perception, then must it also be endowed with a property corresponding to this effect, and this property must be something actual, objectively real in it; other- wise a stone may at times be just as capable of percipient acts. To CLASSIFICATION OF THE MENTAL FACULTIES. 37 Objections examined. — In England the chief psycholojijist darini^ the early part of this century who attacked the doctrine of mental faculties, was Brown. As the right view was sufficiently vindicated then by Hamilton,^- we need not return to refute the former writer or Bailey, who added little of any value on the same side. Mr. Sully, however, may be taken as a representative of recent attacks, so a word in answer to this author may be useful. After premising that the discussion •of the ultimate nature of the " so-called faculties " belongs to Rational Psychology, and so lies outside of his sphere, he continues: "The hypothesis of faculties can, however, be ■criticized from the point of view of Empirical Psychology in so far as it succeeds or does not succeed in giving a clear account of the phenomena. Looked at in this way, it must l)e regarded as productive of much error in Psychology, It has led to the false supposition that mental activity, instead of ■being one and the same throughout its manifold phases is a juxta- position of totally distinct activities ansivering to a bundle of detached powers, somehow standing side by side, and exerting no influence on one anotJier. Sometimes this absolute separation ■of the parts of mind has gone so far as to personify the several faculties as though they were distinct entities. This has been especially the case with the faculty or power of AvilUng."!^ One or two observations m.ay be urged in reply, (i) Mr. Sully, in asserting that all mental activity is one and the same, cannot seriously intend to maintain that the conscious activity known as seeing is identical with that of hearing, or •that cognition is not different in nature from desire. But if he allows these energies to be radically distinct modes of con- deny that property whilst we admit its manifestations, is to assert that the faculty of perception is nothing else than the sum of its acts, and is equivalent to postulating accidents without a substance, •effects without a cause, and to discoursing of phenomena and opera- tions when the subject, the agent, is abolished." {Das Geviiith unci das Gefi'ihlsvermogen dcr neueren Psychologie, von Jungmann, p. 11.) 12 Mctaph. Ixx. 13 Outlines, p. 26. Similarly, Mr. G. F. Stout, Analytical Psycho- logy, Vol. 1. pp. 17 — 21. Mr, Sully is undoubtedly right when he says that discussion of the nature of the faculties pertains to Rational Psychology. But this only proves the evil of " clandestine " Meta- physics. The distinction between the "criticism from the Empirical point of view," which rejects faculties as properties of the mind, putting in their place aggregates of mental states, and the discredited Metaphysics is not very obvious. In fact, such criticism of meta- physical conceptions invariably involves a counter metaphysical ^system of its own. (Cf. Ladd, Philosophy of the Mind, pp. 32, 33.) 38 PSYCHOLOGY. scioiisness under the vague saving clause of " manifold phases," then all that is needed for the establishment of a variety of mental aptitudes in the sense for which we contend is admitted. (2) The description of the theory as involving the absurd view that the faculties form "a juxta-position of totally distinct activities answering to a bundle of detached powers, somehow standing side by side and exerting no- influence on each other," is a mere travesty of the doctrine. Indeed, so far have the supporters of the doctrine been from setting " the faculties side by side exerting no influence on one another," that a great part of the modern attack is based on quite an opposite representation of their view. They are charged in Germany with making the mind the theatre of a perpetual civil war among the faculties ; and Vorlander com- pared the world of consciousness in their system to the condition of the Roman Germanic Empire, when the vassals (the faculties) usurped the functions of the regent (the soul), and were perpetually intriguing and strugghng with each other; whilst Schleiermacher styled the theory a "romance replete with public outrages and secret intrigues." If the faculties are to be annihilated on the charge of being ever- lastingl}' involved in mutual conflict, it is rather hard that they should be condemned at the same time for exerting no influence on each other. The truth is, no such ridiculous view regarding the nature of our mental powers has ever been held by any psychologist of repute, but in talking of the obvious and indisputable fact that our intellectual operations,, emotions, and volitions, interfere with and condition each other, philosophers, like other folk, have been compelled by the exigencies of language to speak as if the faculties were endowed with a certain independent autonomy of their own.. They have, however, of course, from the days of St. Augustine,. and long before, been aware that it is the one indivisible soul which remembers, understands, and wills. ^•^ (3) Even regarding the activities of sense and intellect, which we hold,, and shall prove to be essentially different, the assertion of an imagined and real independence is untrue. The second faculty pre-supposes as a necessary condition of its action the exercise of the first, and is dependent on it for its operation,, whilst both are merely diverse energies of the same simple soul. (4) Finally, the Will is not an independent member, an entity separate from the mind ; it is merely that per- ^* Cf. St. Aug. De TrinUate, Lib. X. c. xi. "Potentia est nihil aliud quam quidam ordo ad actum." (Aquinas, De Anima, Lib. IL lect. 11.) To assign a mental state to a power or faculty is not to explain it, — except in so far as classification may be deemed expla- atioD. See p. 587, below. CLASSIFICATION OF THE MENTAL FACULTIES. 39 fection of the Ego which constitutes it capable of that special form of energizing called willing ; it is the soul itself which wills. The Mind a Real Unity. — There is, however, a tenet implied in our system irreconcilably opposed to the phenomenalist view of Mr. Sully and all other sensationist writers. We hold as a fundamental all-important truth that there exists one real indivisible agent called the Mind, which is something more than the series of events known as conscious states. Those, on the contrary, who maintain that the mind is nothing but an aggregate or series of separate states connected by no real bond, naturally find no place in their theory ior faculties. Mutual Relations of the Faculties. — There remains another question related to our present subject : Which is to be conceived as the most fundamental of our activities? To answer this we must recall our double division of faculties, on the one hand, into sensuous and rational, and on the other hand into cognitive and appetitive. Now of the two former kinds of mental life that of sense is primary. The faculty of sense manifests itself at the earliest age, it extends throughout the entire animal kingdom, and its exercise is always pre-supposed in order to furnish materials to be elaborated by the rational powers in man. Intellect, on the other hand, is something superadded to sense. In all its forms it requires as the condition of its operation the previous excitation of the lower powers, it manifests itself later in life than sense, and it is confined to the human species. Turning now to the other division : Whether is cognition or appetite the more primordial ? But little reflection is required, we think, to make it clear that knowledge is naturally prior to volition. We desire because we perceive or imagine the object of our desire to be good. W^e are drawn or repelled by the pleasurable or painful character of the cognitive act. A sensation of colour, sound, or contact, viewed in its proper character, is a rudimentary act of apprehension, and it may awaken a striving either for its continuance or for its cessation ; an intellectual judgment may similarly give rise to a volition. It is true that some desires manifest themselves in an obscure way without 40 PSYCHOLOGY. any antecedent cognitive representation that we can clearly realize. Tliis is especially the case with the cravings of physical appetite, such as hunger and thirst. Purely organic states which give rise to 3earnings of this kind, however, are rather of the nature of physio- logical needs than properly psychical desires ; and in proportion as they emerge into the strata of mental acts the cognitive element comes into clearer conscious- ness. We may, therefore, lay it down as a general truth that appetite is subsequent to knowledge and dependent on it. These faculties are thus to be viewed, not so mucli in the light of two co-ordinate powers standing side by side, as in that of two properties of the scul, the exertion of one of which bears to that of the other the relation of antecedent to consequent. Feeling. — What position as regards the two powers just mentioned does the so-called third Faculty of Feeling hold in our system ? Feelings understood as a group of emotional states are not, we have already remarked, the offspring of a third ultimate distinct energy, but complex products resulting from the action of both cognitive and appetitive faculties, Feeling viewed simply as pleasure and pain, and such is the only sense in which this form of consciousness has even an apparent claim to the position of a separate facult}', is merely an aspect of our cognitive and appetitive energies. It exhibits itself as a positive or negative colouring, which marks the operations of these powers. As a (]uality of knowledge it must be conceived to be dependent on cognitive activity rather than vice versa. But, inasmuch as it is through this quality that cogni- tion determines the character of the consequent appetite, feeling, or rather the cognition as pleasurably or pain- fully coloured, stands in the relation of cause and effect to the subsequent appetite. Since, liowever, the activity of desire may also be more or less agreeable, and since it may result in satisfaction or discontent, feeling here again stands in the relation of sequela to volitional energy. Feeling thus considered as a qualit}' of conscious acts is of the nature of a variable phase or tone of both cognitive and appetitive activity ; but CLASSIFICATION Of THE MENTAL FACULTIES. 4I when in the position of a dependent accident of the former it may be a causal condition of the latter. ^^ Readings —Classification of the Faculties, of. Sum. i. q. 78. For a very able treatment of the whole subject, see Jungmann'sDas Gemi'ith itnd das Gefi'ihlsvermogen der neueren PsycJiologie. (Freiburg, 1885.) See especially §§ 1—5 and 83—100. The attacks on the Faculties are also exhaustively dealt with by Pesch, Instit Psych §§ 383—390. On the nature of Faculties, cf. Suarez, De Anima, Lib. II. c. i. and Metaph. Disp. 18, sect. 3; Gutberlet,. D/^ PsycJiologie, pp. 3—8; Martineau, Types of Ethical Theories, Vol. II. pp. 10—13; Mercier, Psychologic, pp. 490 — 494. 1-5 This account of the relations subsisting between cognition, feeling, and appetency, which we believe to represent the view of St. Thomas, embraces the elements of truth possessed by both Hamilton and Dr. Bain in the controversy on the subject. Hamilton is right in holding that the cognitive or apprehensive form of consciousness is the most fundamental, and that feeling, i e., pleasure or pain, is dependent on the former, whilst desire is a still later result. There is thus some foundation for his assertion that consciousness is conceivable as cognitive energy void of pleasure and pain, whilst the latter cannot be conceived unless as a quality of the former. On the other hand, through not recognizing the difference between sensuous and intellectual cogni- tion, he falls into the error of supposing that the latter, and some- times even that peculiarly reflex form of it which is known as self-consciousness, is necessarily prior to sensuous pleasure and pain. Dr Bain maintains feeling to be the primordial element, but under this term includes both the pleasurable and painful aspects^ of conscious states, and certain sensations. He is right in holding sensuous life in general to be prior to rational life, but wrong in making feeling under the form of pleasure or pain antecedent to or co-ordinate with cognitive sensibility. PSYCHOLOGY. Book I. Empirical or Phenomenal Psyciiolo';y, Part I. — Sensuous Life. CHAPTER IV. SENSATION. Sensation : Sense and Sense-organ. — The most fundamental and primitive form of conscious life is sensation. Such being the case, sensation cannot, properly speaking, be defined. It may, however, be described as an elementary psychical state aroused in the animated organism by some exciting cause. A sensation is thus a modification, not of the mind alone, nor of the body alone, but of the living being composed of mind and body. The power oi experiencing sensations in general is termed saisibi- lity, while the capacity of the living being for a particular species of sensations is called a sense. The special portions of the organism endowed witli the property of reacting to appropriate stimuli so as SENSATION. 43 to evoke these particular groups of sensations are called sense-organs. A being capable of sensations is described as sentient, or sensitive; and the term sensuous may be applied to all those mental^ states which are acts, not of the soul alone, but of the animated organism. Excitation of Sensation. — The excitation of a sensation usually comprises three stages. First, there is an action of the physical world external to the organism. This action, transmitted in some form of motion to the sense-organ, gives rise there to the second stage. This consists of a molecular disturbance in the substance of the nerves which is propagated to the brain. Thereupon, a com- pletely new phenomenon, the conscious sensation, is awakened. The nature of the external agencies which arouse sensation is the subject-matter of the science of Physics ; the character of the process within the organism which precedes or accompanies the psychical state is studied by the science of Physiology ; while the investigation of the conscious operation itself is the function of Psychology. In describing the action of the senses later on, we will say a brief word on the physical and physiological conditions of each in particular, but a few very general remarks on the nature of the physical basis of conscious life as a whole may be suitable here. 1 We employ the word mental, as equivalent to conscious. In this sense, it is applicable to all states of consciousness, whether cogni- tive or appetitive, sensuous or supra-sensuous. The usage of those scholastic writers who would make this adjective synonymous witli intellectual, seems to us inconveniently narrow, and too much opposed to common language. 44 SENSUOUS LIFE. The Nervous System. — The nervous apparatus of the animal organism is two-fold — the sympathetic system, and the cerebrospinal system. Whilst the former controls organic or vegetative life, the latter constitutes the bodily machinery of our mental states. The cerebrospinal system itself is also composed of two parts or subdivisions, the central mass, and the branches which ramify throughout the body. The central mass, called the cerebro-spinal axis, is made up of the brain and the spinal cord passing from it down through the backbone. The spinal cord consists of a column of white, fibrous matter, enclosing a core of grey, cellular s ibstance. From the spinal cord, between every two vertebrae, there issue forth two pairs of nerves. The nerves proceeding from the front of the spinal column are called the anterior, efferent, or motor nerves, inasmuch as they are the channels employed in the transmission of impulses outwards, and are thus the instruments of muscular movement. The nerves coming from the back of the spine are called the afferent, or sensory nerves, because by their means the molecular movements which give rise to sensations, are conveyed inwards from the various organs of the body. The strands of nerves dividing and sul)dividing as they proceed farther from the trunk branch out into the finest threads through all parts of the skin, so that it is practically impossible to prick any place even with the finest needle without injury to some nerve. The entire surface of the body is thus connected with the brain through the spinal cord by an elaborate telegraph system. {See illustrations at the beginning of the book.) The Brain. — The brain itself is divided into several portions or organs, the functions of which are, however, in many cases but obscurely apprehended. Amongst the chief are the following: 1. The medulla oblongata, which is situated at the root of the brain where the spinal cord widens out on entering the skull. It is, in fact, the prolongation of the spinal cord. From it proceed the nerves of the face and those governing the actions of the heart and lungs. Hence the fatal nature of injuries in this quarter. 2. Higher up and projecting backwards over this into the lower part of the back of the sknll is a large, laminated mass, forming the cerebellum. Its precise functions are still much disputed, but it seems to play an important part in co- ordinating locomotive action. 3. Above and in front of the medulla oblongata is a quantity of fil^rous matter which from its shape and position has been called the " bridge " ov pons varolii. 4. Above all there rises the cerebrum or large brain, exceo:ling in size all the other contents of the skull. It SENSATION. 45 includes several well-differentiated parts lying at its basement, the chief of which are the corpus striaiuni, the optic thalamus, the corpus callosum, and the corpora qiiadrigemina. The cere- brum consists mainly of a soft, pulpy substance of mixed grey and white matter, the former being composed of vesicles or cells, the latter of fibres^ The surface has a very convoluted or crumpled appearance, caused by a large number of fissures. One great furrow, called the median fissure, running from the front to the back of the head, divides the cerebrum into two nearly equal corresponding parts, the right and left hemispheres. Lesser clefts, the chief amongst which are the Sylvian fissure, and ihe fissure of Rolando, subdivide the two hemispheres into lobes or districts, each containing several convolutions. The nerve-cells in the upper cortical surface of the cerebrum seem to be specially instrumental in the memory, or retention and reproduction of sensory and motor impressions. The human brain, when it has reached maturity, exceeds that of all the lower animals in the richness of its convolutions. These latter seem to increase the efficiency of the brain as an instrument of the mind, perhaps, by largely augmenting its superficial area. It is thickly interlined throughout with small blood-vessels, and though ordinarily less than one- fortieth of the weight of the body, it receives nearly one-fifth of the whole circulating blood. Mental operations, as is well known, exhaust a great deal of nervous energy, and vigorous intellectual activity requires a plentiful supply of healthy blood to this organ. Nerves branching mto different parts of the head are given off from the centre of the base of the brain in pairs. The first pair, starting from beneath the corpus callosuui and proceeding forward form the olfactory nerves. The next pair, having their root a little farther back in the optic thalamus, supply the optic nerves. The remaining nerves have their source in the medulla oblongata. The fifth pair supplies the nerves which control the skin of the face and the muscles of the tongue and jaws. The eighth pair, starting still farther back in the medulla oblongata, constitute the auditory nerve. The ninth pair go to the tongue ; and the various nerves issuing from the spinal cord lower down form the tactual and motor nerves of the rest of the body. Nerve-terminals. — The external nerve-ends in the several sense-organs are modified and arranged in various ways so as to react in answer to their appropriate excitants. 13 ut it is not yet agreed among physiologists how far specialization in the structure of the different parts of the nerve-apparatus is required in order to respond to the different forms of sensori- stimuli. 46 SENSUOUS LIFE. Sensori-motor action. — The ordinary process of movement in response to sensations then is of this kind. An impression, c.f^., tactual, gustatory, or visual, wrought upon the end-organ of an afferent nerve, is transmitted in some form of motion to a centre in the brain. When it arrives there a sensation is awakened. This state of consciousness now produces an impulse which flows back along a motor nerve and causes some movement. Thus, if a man treads on my foot, I pull it awa}^ even involuntarily. Reflex-action. — A simpler form of motor-reaction, however, is exhibited in reflex -movement. Here the impression is reflected back along a motor nerve from the spinal cord or some inferior centre before reaching the great terminus in the brain, and there is an appropriate movement in response to the stimuli without the intervening conscious sensation. Thus, tickling the sole of the foot causes convulsive movement even after the spine has been broken and conscious sensibility has been extinguished in the lower part of the body. Properties of Sensation : Quality, Intensity, Duration. — The most prominent feature by which sensations of the same or different senses are dis- tinguished from each other, is that of quality. The sensations of sound are thus of a generically different quahty from those of smell, while the feeling of blue is of a specifically distinct quality from that of red. These states ma}^ also vary in tone, or pleasurable- ness and painfulness. Besides differing in quality, sensations may also vary in intensity, and duration. By the intensity of a sensation is understood its vividness, its greater or less strength in consciousness. The degree of intensity depends partly on the force of the objective stimulus, and partly on the vigour of attention. The duration of a sensation means obviously the length of time during which it persists in existence. This is determined mainly by the continuance of the stimulus. The duration of the sensation is not. SENSATION. 47 however, always either equal to or simultaneous with that of the stimulus. A certain brief interval is always required between the irritation of the organ and the birth of the mental state, and the latter continues for a shorter or longer period after the cessation of the former. A certain lapse of time is consequently necessary between two succes- sive excitations in order that there be two distinct sensations. Thus, in the case of sight, if the action of the stimulus be repeated oftener than five times in the second, it ceases to be apprehended as a series of separate events, and instead, one con- tinuous sensation is aroused. The ear can distin- guish as many as fifteen successive vibrations in the second, while the recuperative power of taste and smell, after each excitation, is far lower than that of sight. Composite stimuli. — It is erroneous, however, to speak of the continuous sensation produced by these repeated excitations as a CGinpound sensation arising from the combination of a number of simple sensations. It is only by an inaccurate metaphor that unextended mental states can be described as blending, or mixing, after the manner of liquids or gases ; and there is, moreover, nothing to show that the supposed constituent elementary states ever came into existence. The simplest and briefest sensation has for its physical condition a neural process, divisible into parts ; it would, however, be absurd to speak of it as composite, on this account. In the case of a continuous sensation of sound, or colour, arising from an intermittent stimulus, the SENSUOUS LIFE. physical and physiological conditions may be more complicated, but the mental state felt to be simple must be described by the psychologist as such.^ Somewhat similarly, in the case of touch, a certain interval of space, variable in different portions of the body, must exist between the parts of the organism affected by two stimuli, m order that these may be felt as distinct. The capacity of sensation for variation in intensity and duration has suggested in recent times the attempt to secure exact quantitative measurement of mental pheno- mena, and the title of Psycho physics has been allotted to this line of investigation. Cognitive character of Sensation — The features hitherto described, including even pleasantness or painfulness, are merely aspects or accidental pro- perties of sensation. Its essential nature lies in its cognitive quality. The intensity, duration, and emotional tone of a sensation, exist only as they are known. They are of a variable and adjectival nature. They determine and modify, but they do 2 The "objective " analysis of mental states by Mr Spencer and M.Taine is thus illusory. If states which consciousness— the only possible witness concerning such facts — declares to be simple, are to be reduced to units of the character of nervous shocks, because the action of the physical agent is of a composite character, then we certainly cannot stop at the feeling of a " shock," as the unit. The briefest and simplest sensation of the colour of violet, which involves between six and seven hundred billions of vibrations in the second, must be resolved into an incredible number of unconscious units of consciousness, for the existence of none of which, of course, is there any evidence A knowledge of the physical conditions of mental states is valuable, but conscious elements affirmed to be simple by introspection, must be accepted as such by the psychologist. "Mental facts," as Mr. Mark Baldwin urges, "are simple states, and they are nothing independently of the mind whose states they are." (Cf. Senses and Intellect, pp. gS— io6; also Dr. Mivart, Nature and Thought, 2nd Edit., pp. 89—92.) See also pp. 510—512, below. SENSATI0>^. 4q not constitute the essence of a sensation. A sensa- tion is in itself an elementary mode of consciousness of a cognitional character. Knowledge, however, may have reference either to extra-organic, or to intra- organic objects and events. We may be cognizant of something other than ourselves, or of the states of our own sentient organism, and different censes stand higher and lower in regard to these different fields. In sight, in the muscular sense,^ and in the tactual sensations of pressure, knowledge of external reality is the prominent feature ; in hearing, taste, smell, and the organic feelings, the sensation is a cognition, which originally bore a subjective character. In the case of these latter faculties, the pleasurable or painful aspects of sensa- tions frequently rise to great importance ; and on some occasions the sensation becomes mainly a cognition of pain, or, more rarel}^ of pleasure. Sensation and Perception. — Tiiis distinction between the objective and subjective import of the sentient act has caused the two terms, sensation and perception, to be contrasted witli each other. Sensation, as thus opposed to perception, is variously defined to be, tlie modification of the sense viewed merely as a subjective state, the consciousness of an affection of the organism, or the feeling of pleasure or pain awakened by the stimulus. Perception^ is described as the objective " This term is used to denote the power of experiencing sensa- tions of resistance or impeded energy and movement. Its nature will be discussed in the next chapter. ^ The word perception, or rather, the Latin verb percipere, was originally used in a wide sense to denote any form of apprehension or comprehension, whether sensuous or intellectual. Later on. it became limited to sensuous apprehension, and was employed by Reid, in contrast to the term sensation, to designate the sensuous cognition of something as external to us. Sensation originally meant the process of sensuous apprehension considered as revealing to us both itself as a subjective state, and the objective quality to which it corresponded. By Reid it was confined to the former significa- 50 SENSUOUS LIFE. knowledge, the apprehension of external reality given in the sentient act ; or, as the act by which we locahze or project a sensation or cluster of sensations, actual and possible, into the external world. . This separation of the two terms is convenient for bring- ing out the difference between the developed form of cognition exhibited by sense in mature life, and the vague kind of apprehension afforded in the earlier acts of the sentient powers : but the distinction is one of degree, not of kind. In the most rudimentary sensations of pressure and of colour, there is a cognition of something other than self, and though rude and indefinite in character, this is still an act of objective kTiowledge. Consequently, there is already here perception, in the modern signification of the term. This vague act receives exacter definition as we advance, and in later years the quality perceived by the sense is cognized as situated in a determinate place, and accompanied by other qualities. Such further determinations, are, however, the result of other sensations, and if no one of them revealed external reality to us, the aggregate could not do so. This subject will be better understood when we come to treat of the nature of Perception. Some writers define Sensation as the feeling of pleasure or pain attached to an act of sensuous apprehension, but very few, if any, adhere consistently to this interpretation. When, for instance, the sensations of the different senses are spoken of, and their various properties, quality, intensity, tone, dura- tion, and the rest, are described by psychologists, sensation does not mean the pleasurable or painful aspect of certain mental states, but these states themselves. It is only when used in this narrow signification, as a feeling of pleasure or pain, that sensation and perception can be held within certain limits to stand in an inverse relation to each other.^ tion.and thus explained : "The agreeable odour (of a rose) which, I feel, considered by itself without relation to any external object, is merely a sensation. Perception has always an external object, and the object in this case is that quality in the rose which I discern by the sense of smell." The later sensationalists {e.s;;. Mr. Sully, Outlines, c. vi.), inverting the doctrine of Reid and Hamilton, that perception is the apprehension of a real external quality, describe this act as an ejection or projection out of the mind of a sensation carrying with it a cluster of faint representations of other past sensations, the whole being "solidified" or "integrated" in the form of an object. On the terms sensation and perception, cf. Hamilton, On Reid, Note D, also Metapli. Vol. H. 93—97. 5 Hamilton explains Reid to mean by perception. " the objective knowledge we have of an external reality through the senses ; by sensation, the subjective feeling of pleasure or pain with which the SENSATION!. 51 The modification of a sensuous faculty is thus, in its simplest form, of a percipient character, and in the case of vision and touch, the sensation from the beginning possesses a certain objective refer- ence. A sensation viewed in this way as a modifi- cation by which the mind is made cognizant of a material quality of an object, was called by the schoolmen a species sensibilis. The Scholastic Doctrine of Species.— The doctrine of species has been attacked and ridiculed by man}- modern writers, and this in a manner which sfiows how widespread and profound, even amongst students of philosophy, is the ignorance regarding the most familiar terms of scholastic writers. Democritus and Epicurus formerly taught that we know objects by means of minute representative images which stream off from their surface, and pass into our soul through the channels of the senses. The Latin word species, meaning an image, was used by their Roman disciples to signify these volatile images. Aristotle and his followers, however, rejected the theory of a physical efflux of species, and taught instead, that objects effected modifications in the mind by acting on the sense-organs through motions in the intervening media. The term species was later on employed to denote these modi- fications by which the mind is made to apprehend the exterior object. In this sense, which is that accepted by the greatest philosophers of the middle ages, such as St. Thomas, Albertus organic operation of sense is accompanied," and adopting this view he enunciated the law that above a certain point the stronger the sensa- tion the iveakcr the perception, and vice versa. He seeks to establish this general opposition by a comparison (a) of the several senses, and {b) of different impressions within the same sense. Confined to sensuous apprehension, the formula seems to be approximately true, although it is pain rather than pleasure which interferes with cognition. As a generalization applicable to higher intellectual forms of cognitive activity, it does not hold. Consciousness is not, as Hamilton seems to imply, a fi.xed quantity where increase in cognition involves decrease in feeling. This is in direct opposition to the doctrine adopted by Hamilton himself from Aristotle, that pleasure is a reflex of mental energy. In the view of the Greek philosopher, keen and intense pleasure accompanies vigorous intellectual activity, and the greatest and best pleasure is the necessary sequela of the exercise of the highest form of cognitive energy. (Cf. Hamilton, Metaph. pp. 93 — 105.) 52 ■ SENSUOUS LIFE. Magnus, and Scotus, the species is not an entity which ha& immigrated into the mind from the object, but a modification or disposition awakened in the mind by the action of the object. They teach, moreover, that this mental modification is not what is primarily perceived in the act of simple appre- hension. The mind, they hold, directly tends towards the objective reality; and only by a reflex or concomitant act does it cognize the mental state as such. With them. Species non est id quod primo percipihir, sed id quo res percipitur. It is the medium vel principium quo, non ex quo, res cognoscitnr. In other words, the species is not an intermediate representation from which the mind infers the object, but a psychical modification by which the mind is lii^ened, or conformed, to the object, and thus determined to cognize it.° Intentionalis. — The adjective intentionalis was added to the term species to signify that the cognition, though truly reflecting the external object, does not resemble it in nature. The mental modification was held to be merely a psychical or spiritual expression of the material thing. Resemblance is of many kinds. A photograph, or a statue, is, in a certain sense, utteily unlike a man formed of flesh and blood; the blind ^ If the primary object of cognition were the mind's own unex- tended modification, idealism and relativism would be inevitable. " Qnidam posuerunt, quod vires, quae sunt in nobis cognoscitivae nih 1 cognoscunt, msx proprias passiones, puta, quod sensus non sentit nisi passionem sui organi, et secundum hoc intellectus nihil intel- ligit, nisi suam passionem, scilicet speciem intelligibilem in se receptam ; et secundum hoc species hujusmodi est ipsum quod intelli- gitur. Sed haec opinio manifeste apparet falsa ex duobus. Primo quidem, quia eadem sunt quae intelligimus, et de quibus sunt scientiae ; si igitur ea, quoe intelligimus essent solum species quae sunt in anima, sequeretur quod scientiae omnes non essent de rebus, quae sunt, extra animam, sed solum de speciebus inttlligibilibus quae sunt in anima. Secundo, quia sequeretur error antiquoruni dicentium, omne quod videtur, esse verum ; et similiter quod contradictoriae essent simul verae ; si enim potentia non cognoscit ni^i propriam passionem, de ea solum judicat . . . puta si gustus non sentit nisi propriam passionem, cum aliquis habens sanum gustum judicat mel esse dulce, vere judicabit; et similiter si ille, qui habet gustum infectum, judicet mel esse amarum vere judicabit ; uterque enim judicabit secundum quod gustus ejus aflicitur. . . . Et ideo dicen- dum est quod species intelligibilis se habet ad intellectum ut quo intelli£;it intellectus. . . . " Sed quia intellectus supra seipsum reflectitur, secundum eandem reflexionem intelligit et suum intelligere et speciem qua intelligit. Et sic species intellecta sccundario est id quod intelligitur. Sed / J ^7/oi intelligitur /n/«c) est res cujus species intelligibilis est simiUtudo." {Sum. la. q. 85. a. 2.) SENSATION. 53 man's representation of a circle by the sense of touch, is very different from the visual image of the same figure ; the intel- lectual ideas aroused by the words, "equality," "colour,'^ "square," must be widely divergent from both the image and the reality to which they correspond. Yet, in spite of these unlikenesses, there exist genuine relations of similarity between such pairs of things as those just mentioned. The scholastic writers adopting this view, taught that our know- ledge, although in itself, as a mental activity, opposed in nature to material reality, docs, nevertheless, truly inirror the surrounding world. They held that though neither the tactual nor the visual image resembles in nature the brass circular substance presented to the sense, yet both accurately reflect and are truly like the external reality ; and they called these mental expressions of the object species intcntioiuilcs. Species sensibiles et intelligibiles. — Furthermore, as the schoolmen held the human mind to be capable of two essentially distinct kinds of cognition, sensuous and intellec- tual, they termed the apprehensive acts of the former species sensibiles, of the latter species intelligibiles vel intellcctuales. In \ the genesis of the species they distinguished two moments ci 1 stages. The modification of the sensuous faculty, viewed as 1 an impression wrought in the mind by the action of the object, was named the species impvessa. The reaction of the mind as an act of cognitive consciousness was styled the species expressa. The latter term designated the sensation considered as a completed and perfect act of consciousness elicited by the soul ; the former indicated the earlier stage of . the process, the alteration in the condition of the mind looked \ at as an effect of the action of the object." The species proper, ^ however, whether impvessa or expressa, was an affection of the mind. The term species corporal is was sometimes used to signify the physical impression or movement produced by the object in the organism, but the strict meaning of the word species, and the only meaning of the term species intentionalis, was the mental state. Thus, neither the image of the object depicted on the retina of the eye, nor the nervous disturb- ance propagated thence to the brain, but the conscious act finally awakened, was held to be the true species or species intentionalis. True doctrine. — Rejecting the interpretation of the species as roving images, and every theory conceiving them as repre- sentations mediating between the object and the cognitive "^ The existence of the species impvessa ]" proved by the fact of memory. That the alteration or modification wrought in the soul by the act of perception must persist in some form, is established by the facility of representation and recognition 54 SENSUOUS LIFE. faculty, the thought embodied in the doctrine is thoroughly sound. Unless we are prepared to maintain that our soul is born with all its future knowledge ready made, and wrapped up in innate ideas, we must allow that the physical world does somehow or ether act on our faculties, and that our perceptions are due to the influence of material objects upon us. The mind does not determine all its own modifications, and the strongest volition is unable to make the deaf man hear a word, or the blind man see a colour. But this is to admit that the faculty is stirred into conscious life and informed by dispositions wrought in it by the perceived object. Further, unless we are ready to adopt the position of absolute scepticism, we must hold that knowledge does somehow correspond to reality. There is not a merely arbitrary con- nexion between the object and its apprehension. The latter is a true, though psychical expression of the former. This subject will be more fully dealt with hereafter, but we have said enough to justify the doctrine of species iutentionales, as understood by St. Thomas, and the leading philosophers of the school.^ The modern writer may prefer to describe the perception of a triangle as a modification of the mind mirroring or reflecting in terms of consciousness the external object, but this is only the old doctrine in other phraseology. Experimental Psychology. Psycho-physics.— The ineasuremcnt of mental states. — If one ounce be added to a weight of three ounces placed on our hand resting upon the table, \ve can just distinguish the new sensa- tion from the old. A single voice also makes a per- ceptible increase in the sound when added to a musical trio. If, however, we add a single unit to a weight of thirty ounces or to a chorus of twenty voices, no difference can be felt. By observing and comparing sensations produced by stimuli varying in intensit}', a German physiologist, Weber (1834), showed that the incvemcnt necessary to he added to a given stimulus in order to awaken a sensation consciously distinguishable from the former ^ Kven Hamilton confounds the maintenance of species with the doctrine of mediate perception, and so looks on St. Thomas and the great body of the schoolmen as representationalists or hypothetical realists. (Cf On Reid, Note M, pp. 852 — 857.) The passage cited from St. Thomas, p. 52, refutes the charge. For a full treatment of the subject, see Sanseverino,D)';/p. cit. p. 470; James, op. cit. p. 88. SEMSA TtON. 6t experiments and then climinatccl, the lengtli of the strictly psycho-physical portion of the whole reaction, it is alleged, may be estimated. Wundt gives as average total reaction-time of a series of experiments, for impressions of sound, 0-128 of a second; for light, 0*175; for touch sensations, o-i88. But Exner, Hirsch, and others give different figures. Study of these investigations goes to prove that the reaction-time varies much with different individuals. On this fact is based the "personal equation" of different observers which have to be taken into account in certain delicate astronomical observations. Further, it seems clear that practice shortens the reaction-time very considerably, and that expectant attention also diminishes it. On the other hand, fatigue increases it ; intensity of stimulus, too, causes a difference ; the v/eather, the general health of the individual, and the nature of the stimulus also modify the rapidity of the reaction. Many writers exhibit a laudable enthusiasm for this new department of investigation. We confess, however, we cannot share in their hopeful expectations of psycho- logically valuable future results; nor does the character of those yet reached justif}^ the very roseate anticipations entertained. For these experiments after all furnish physiological rather than psychological information. They measure the speed or intensity of nervous processes with which certain mental operations may, or may not, be concomitant ; but they throw no real light on the quality of these latter. They are in no true sense a record of the rapidity of thought, and if employed as a means of measuring intelligence or mental development, they are utterly misleading. They may indeed help to indicate the delicacy or discriminative sensibility of the sense- organs and nervous system, but the extent to which the reaction-time can be shortened by a little practice and other slight alterations of tlie conditions proves what a ver}^ insecure standard it would be even in this respect.^'' ^■^ Mr. Sully writes: "Those researches show that mental capacity in general grows between the age of six and seventeen — at 62 SENSUOUS LIFE. Readings. — On the physiology of the nervous system, see any of the elementary text-books of Physiology. Carpenter's Mental Physio- logy, c. ii., and R. S. Wyld's Physics and Physiology of the Senses, Pt. IV. treat the subject well, with special reference to Psychology. However, by far the best and most exhaustive work on the physio- logical conditions of mental life, which has yet appeared in English, is Professor Ladd's Elements of Physiological Psychology. The German reader will find an able and interesting treatment of the whole subject of sensation by Gutberlet, Die Psychologic, pp. 12—48. On the history of the terms sensation and perception, cf. Hamilton, Meta- physics, Vol. II. pp. 93 — 97, and Notes and Dissertations on Reid, Note D. The subject of species is treated in all the Latin manuals ; perhaps, Sanseverino's Dynamilogia, pp. 373 — 403, is amongst the best. Suarez, De Anima, Lib. III. cc. 2, 3, discusses the matter at length. See also J. Rickaby, First Principles, pp. 8, seq. An admir- able exposition of the Scholastic doctrine of intellectual knowledge by means of specks is contained in Kleutgen's Philosophic der Vorzeit, U 18-52. first quickly, then more slowly, &c." [Teachers' Handbook of Psychology, p. 94, 4th Edit. ; cf. Scripture, loc. cit. pp. 134, 169.) The value of such experixnents as a standard of " mental capacity " is evinced by the fact that the reaction-time of a pauper, aged 77, experimented on by Exner, was reduced by a little practice from 0-9952 to o 1866 of a second ! The explanation is simple enough. The " mental capacity " of the old man was pretty much the same at the end as at the beginning of the experiments, but his nervous apparatus had acquired the " knack " or facility of reacting in less than one fifth of the original time. Similarly, children may exhibit varying aptitudes, inherited or acquired, in regard to such operations, as they may vary in their power of acquiring any ordinary reflex- action, with little or no relation to their intellectual ability. On the whole subject, cf. James, Vol. I. c. iii. and Ladd, Part II. c. viii. CHAPTER V. THE SENSES. How many External Senses ? — A group ci sensations containing a number of features in common are assigned, we have said, to a special sense. The question may now be raised, how many senses have we ? There has been a good deal of disagreement on the point among modern writers, but the decision arrived at does not seem to us to be of very much importance, provided that the various forms of sensibility be recognized. The specialization of the organ, the nature of the stimulus, and the quality of the consciousness, have each been advocated as the true principle of classi- fication, and different plans have consequently been drawn up.^ In favour of the old-fashioned scheme ^ Following Kant, Hamilton styles the five special senses the sensus fixus, and adds to them a sixth general sense, the sensiis vagus, common feeling, the vital sense, or aen^Fstiesis, embracing the feelings of temperature, shuddering, health, muscular tension, hunger, and thirst, &c. Dr. Bain's scheme stands thus: a. Muscular sense. B. Six classes of organic sensations: (i) of muscle, (2) of nerve, (3) of circulation and nutrition, (4) of respiration, (5) of temperature, (6) of electricity, c. The five special senses. G. H. Lewes empha- sized the importance of the systemic sensations, e.g., feelings of digestion, respiration, temperature, circulation, &c. Mr. Murray, who adheres consistently to distinction of organ as his principle of division, gives this classification : I. The Five Special Senses. II. General Senses, a. Connected with a single organ: (i) muscular 64 SENSUOUS LIFE. of the five senses, taste, smell, hearing, sight, and touch, it may be urged that it recognizes the obvious structural differences of organ, to a great extent the most marked differences in the quahty of the con- sciousness, and also generic differences in the phenomena apprehended. The eye reveals to us colours, the ear sound, the nose smell, the tongue taste, and touch pressure. In the language of the schools, the formal objects of the several senses are generically different. However, if this classification be adopted, it must be remembered that under the sense of touch are comprised many groups of mental states importantly different in quality, and frequently attached to parts of the organism of very specialized character. Method of Exposition. — The most convenient order of procedure will be to start from the simpler and more easily described faculties, and to go on gradually to those of a higher, more varied and complex nature. In our exposition we will adopt the usual plan of saying a few words on the formal obj-ect of each sense, on the physiological machinery employed, and on the character of the consciousness awakened. In dealing v/ith this last phenomenon, which is the proper subject-matter of Psycholog}', sensations, (2) pulmonary sensations, (3) alimentary sensations. B. General sensations not confined to a single organ: (i) of tem- perature, (2) of organic injuries, &c., (3) of electricity. The true principle, however, if it could be satisfactorily applied, would be the quality of consciousness. Differentiation of organ is an extrinsic physiological consideration. Still the difficulty of determining how much qual'.tative difference justifies the assumption of a special s'.ose renders the former princiyli of little value once we depart from th.e old scheme oi five senses. THE SENSES. 65 the two chief features to be attended to are what have been styled the emotional and the intellectual aspects of the sense. By the former is meant, the susceptibiHty of the faculty to pleasure or pain ; by the latter, its efficiency as an instrument of know- ledge of the external world. The use of the epithet *' intellectual," however, is very inaccurate here, and still more so when applied to individual sensa- tions. The Intellect is a faculty essentially distinct from sensuous powers, and its activity, just as that of any of the senses, may possess a pleasurable or painful character. It will accordingly be more appropriate to term this property of a sense or sensation its cognitional aspect. Taste. — Physiological conditions. — The formal object of the sense of taste is that quality in certain soluble substances in virtue of which they are called sapid. The organ of taste is the surface of the tongue and palate. Over these surfaces are dis- tributed the gustative papillce, from which nerves proceed to the brain. In order to excite the sensa- tion, the body to be tasted must be in a state of solution in the mouth. The precise nature of the action of the sapid substance on the papillae is unknown, but it is probably chemical. Sensations. — The sensations of this faculty do not possess such definite qualitative differences as to fall into well-determined groups, and consequently there is no general agreement in the classification of different tastes. The proper pleasure of the sense is sweetness; its proper pain bitterness. Most F 66 SENSUOUS LIFE. gustatory sensations involve elements of tactual, nasal, and organic feelings. Thus, acid, alkaline, fiery, and astringent tastes, are in part the effects of tactual stimulation ; feelings of relish and disgust are traceable to the sympathy of the alimentary canal ; and sensations of smell also influence our estimation of the sapid qualities of many substances. The cognitional value of this sense is very low. Con- tinuous stimulation rapidly deadens its sensibility ; its recuperative power is tardy, its sensations are wanting in precision, and they can be but very imperfectly revived in imagination. The main grounds of its cognitive inferiority, however, lie in its essentially subjective character. Abstracting from the information afforded by concomitant tactual sensations, taste originally gives us no knowledge of external reality, and, consequently, with the exception of the vague systemic feelings of the organism, it must be ranked lowest as a medium of communication with the physical world. On the other hand, viewed from the standpoint of feeling, this sense is capable of intense but short- lived pleasure and pain. Though the lowest of our faculties in point of refinement, and the most subject to abuse, its great utility as a guide in the selection of food throughout the animal kingdom is evident. Smell. — Physiological conditions. — Odorous par- ticles emitted from gaseous or volatile substances constitute the appropriate stimulus of this sense. The organ of smell is the cutaneous membrane lining the inner surface of the nose. The action of THE SENSES. 67 the odorous substance is probably of a chemical character, and the simultaneous inhaling of the air is requisite for the production of the sensation. In the act of inhalation the stimulating particles are drawn through the nostrils over the sensitive surface. Even the strongest smelling substances are not perceived as long as we hold our breath. Sensations. — This sense resembles that of taste in many respects. Vagueness is a marked feature of each; continuous excitation renders both obtuse; their recuperative power on the cessation of the stimulus is weak; and both are originally of a like subjective character. The close affinity of the two faculties is exhibited in the difficulty of determining how far the recognition of a particular substance is due to taste, and how far to smell ; and in the readiness with which most of the adjectives, such as sweet, bitter, pungent, primarily qualifying sensations of taste, are transferred to those of smell. The attempt to distinguish port wine from sherry, apart from sight and smell, is a familiar method of illustrating the former. The delicate susceptibility of smell to some kinds of stimulation is, however, very surprising. The merest trace of a drop of oil of roses awakes a pleasurable feeling, and as infinitesimal a particle as the one thirty- millionth part of a grain of musk is perceptible. The delicacy of this faculty in the dog and other brute animals,- as is well known, far exceeds what - Cf. Bernstein, The Five Senses, p. 290. He says that some animals can, when the wind is favourable, scent the huntsman several miles away. The number and the minuteness of the volatile particles which proceed from objects perceivable at such distances pass comprehension. 68 SENSUOUS LIFE. it attains in man. Just as in the case of taste, the sensations of smell may be of an extremely agree- able or disagreeable character. They stand higher, however, in order of refinement. They are, too, more easily revived in imagination ; and, being awakened by objects at a distance, these sensations, like those of sight, assume the character of pre- monitory signs of other future experiences. In this way the sense of smell comes to surpass both organic and gustatory sensations, as an instrument of ex- ternal perception. Touch. — Under the generic sense of touch are comprised a variety of classes of feeHngs widely different from each other. Consequently, very early in the history of Psychology, we meet wdth discus- sions as to whether this term does not include several specifically distinct senses. Aristotle^ called attention both to the close relationship of taste with touch, and to the divergent nature of sensations of tem- perature, of softness and hardness, and of contact proper. It would certainly seem that sensations of temperature, differing so much in quality from those of touch proper, awakened, moreover, by distant objects, and seated either in different nerves or different properties of nerve, from those of our tactual feelings, have as strong claims to be con- sidered the utterances of a separate sense as our ^ Aristotle, in the De Anima, II. 11. 22 — 24, holds a plurality of senses to be contained under the generic faculty of touch. Else- where, in the De Gen. Animalium, he seems to adopt the monistic view. St. Thomas, however, prefers to look on these sensations as merely differenv classes of feelings comprised under one tactua. sense, the formal object of which has not received a definite namel (Cf. Sum. i. q. 78. a. 3 ; also SchifTini, Disp. Mctaph. Vol. I. p. 322.) THE SENSES. 69 gustatory states. Since, however, every proposed subdivision of touch into separate senses appears open to grave objections, and since the question is really of no very great importance, the most con- venient plan will be to distinguish and describe separately the leading modes of sensibility included under touch in its widest sense, without deciding whether they should be assigned to different faculties. These forms of consciousness are : (i) the organic sensations, (2) the sensations of temperature, (3) touch proper, and (4) the muscular sensations. The Organic Sensations, Common Sensibility, Ccenaesthesis, or the Vital Sense.— Under these various designations are included the numerous modes of sensuous consciousness attached to the organism as a whole, or to particular portions of it. Their essential function is to inform us, not of the properties of the extra-organic world, but of the good or ill condition of our own body. Prominent among them are the systemic sensations, comprising those of the alimentary canal, such as the feelings of hunger, of thirst, and repletion, the sensations of respiration, of circulation, and such other states as are normal to the system. In addition to these, the chief remaining organic sensations are those arising from disease, and from laceration or fracture of any part of the organism. Estimated from a cognitional point of view, the organic sensations are of little importance. With the exception of particular hurts, they are of an indefinite and obscure character. They can be but very feebly reproduced in imagination. Being in great part beyond the range of touch and sight, they are vaguely and imperfectly localized, and they give us practically no information regarding the external world.* On the other hand, as sources of ^ Common sensibility has, however, great importance from an intellectual standpoint in this respect, that it is the source of much error. It may seriously distort men's judgments. Peace and war have at times depended on the Prime Minister's digestion. 70 SENSUOUS LIFE. pleasure and pain, they possess immense influence over the tenour of our existence, and they are of the greatest utihty as guardians of our physical health. Sense of Temipersiture.— Physiological conditions.— Diffused throughout the organism as a whole, yet specially seated in the skin, the sense of temperature has claims to be grouped botli with the organic sensa- tions and with the sense of contact proper. Some writers have maintained that our consciousness ot temperature is dependent on a set of nerves distinct from those employed in tactual sensation. This is not yet absolutely proved, but that the properties of the nerve-fibres involved are completely different^ is shown by the fact that either class of feelings may be almost entirely suspended, whilst the other remains compara- tivel}^ unaffected. Sensations. — As our consciousness of temperature is relative to that of our own person, this sense can afford little assurance about the absolute heat or coldness of an external object. When the environment is of the same temperature with that of the part of our body exposed, we are unconscious of it. If we pass into the chill night air from a hot room, we are keenly aware of the change, but even before the skin of our face and hands is reduced to the same degree of warmth as the surrounding atmosphere, we become habituated to the stimulus, and consciousness of temperature almost disappears. It has been found, however, that wdthin a moderate range, fine variations can be noticed in comparing the temperatures of two bodies ; and the hand is able to detect a difference of J a degree Cent, in two vessels of water. The effect of heat or cold increases with the extent of the surface exposed. Thus, water which feels only comfortably warm to the hand '' Recent ingenious experiments by Goldscheider and other physiologists, seem to show not merely that the nervous end- apparatus of temperature sensations differs from that of pressure and of pain, but even that there are in the skin distinct " heat-spots " and "cold-spots"— minute localities sensitive to heat but not to cold, and conversely. This appears surprising when we recollect that to the physicist heat and cold are purely relative. (Cf. Ladd, op. cit. pp. 34^—350) THE SENSES. ' 71 or arm, may cause severe pain if the whole person is immersed. In extreme heat and cold, the sensation of temperature proper disappears, and, instead, in both cases, a like feeling of keen organic pain ensues. In polar voyages, the sailors speak of cold objects burning their hands. Viewed generally, this sense is of little cognitive, but of much emotional significance. Its appropriate pleasure lies in moderate warmth, its specific pain in extreme heat and cold. Sense of Contact or Passive Touch. — Physio- logical conditions. — The organ of this sense consists of a system of papillcd distributed over the surface of the dermis, or under-skin, which covers the surface of the bod3\ Above this dermis lies the cuticle or external skin, which acts as a protection for the papillae, nerves, and veins lying beneath. From the papillae proceed nerve- fibrils to the spinal column and thence to the brain. The proper stimulus of the sense of touch is simple pressure on the external skin. In order that a sensation be awakened, the effect of the physical excitation at the surface must be transmitted along a sensory nerve to the brain. If the nerve is severed above the point of irritation, no mental state is elicited, and if an intersected nerve is irritated above the point of sever- ance, the cause of the sensation aroused is judged to be at the old peripheral extremity. From this it has been inferred that the sensation occurs not at the surface, but in the brain or central sensorium, and that it is by experience we come to learn the seat of the exterior impression.*^ If this doctrine is to be interpreted as ^ The doctrine that the true seat of sensation is a Hmited internal centre is as old as Aristotle. (Cf. St. Thomas, Comm. De Anima, II. 11. 22, 23.) He holds there that the heart is the proper locus of tactual sensation, the intervening flesh being only a medium differing from the air or other external media by the fact that it is not an accidental but a connatural instrument. That our apparent consciousness to the contrary does not suffice to decide the question, he shows by pointing to the fact that if a covering or rigid substance is placed between the skin and the excitant, we then localize the sensation at the outer surface of the new tegument, and not in the skin. In the De Gen. Animalium, however, he seems to pass into the other view. (Cf. also P. S. Seewis, Delia Conoscenza Sensitiva, pp. 368 — 372.) Dr. Stockl is among the most distinguished of 72 SENSUOUS LIFE. implying that peripheral stimuli were originally localized by us in the brain, or that the soul is confined within the limits of the brain chamber, and that the action of the excitant impinges upon it there, then it must be rejected as warranted neither by ph3'siological nor psychological evidence. The fact, however, may be held to show that our ability to localize impressions is very largely due to experience, and that our original capacity in this respect was very imperfect. The physiological process which is the proximate cause of sensation contains three stages. The first is the peculiar action set up in the exterior terminals of the nerves of the various senses. The specialization in structure and constitution of these apparatus, which modern Physiology has brought into prominence, demonstrates the significance of this moment in the operation. The second step is the transference of the excitation by means of a molecular change along the nerve to the brain. Here the last item in the physical process takes place, but of its character we know virtually nothing. On its completion, however, the soul which animates equally every part of the nervous system, and, in fact, every part of the organism, reacts in the form of a conscious sensation. The quality of this mental state is affected by the portion of the body in which the physiological process has taken place ; the feeling, for instance, of an impression on the leg or the back is different from that of a similar impression on the arm. Nevertheless, the sensation is not definitely localized from the beginning at the precise spot of peripheral stimulation ; the exact site of the starting-point of the neural change is learned by experience. This subject will, however, be discussed more fully in a future chapter. Cognitional Value of Touch. — The sense of touch stands very high as a medium of external perception, •/et its sensations possess in many respects the vague- modern scholastic writers who support the view that sensation is elicited, not in the external parts of the sense-organ, but in the brain. (Cf. Empirische PsycJwlogie, § 6, n. 12.) THE SENSES. 73 ness and want of precision wliich cliaracterize the faculties hitherto dealt with. Thus there is compara- tively little variety in kind among our tactual feelings which are mainly discriminated as rough, smooth, gentle, and pungent. They possess, however, a delicate sensibility to differences in the intensity and duration of the stimulus, and still more important in this con- nexion, they are endowed with fine local characters on account of which they come to be referred with great accuracy to the place of excitation. By means of this property the mind is able simultaneously to apprehend co-existing points, cognizing them as separate ; and in this apprehension there is the presentation of extended space. The simplest form of tactual sensation, such as that of the contact of a feather, does not seem to involve the feeling of pressure, and this is sometimes styled the sense of contact proper, but it scarcely passes beyond the range of the organic sensations. The vast majority of our sensations of contact are sensations of pressure, and this element must be included under the sense of touch. Discriminative Sensibility. — The sensibility of the skin to purely tactual pressure varies in different parts of the body. If a particular point on the hand is tested, we can, according to some writers, notice the difference between two successive pressures when it equals the ■^^th of the original weight. Pressures on two different hands can only be observed when one exceeds the other by "I. The capacity of touch for local discrimination also varies in different parts of the skin. The method of experiment adopted by Weber, was to place the two points of a pair of compasses on the part to be examined, and then to widen or narrow them until the two points could be just felt as separate. It was found that along portions of the back and forearm the points of the compass required to be from two to three inches apart in order to be distinguished, whilst on the tips of the fingers and the tongue an interval of one twelfth and one twenty-fifth of an inch sufficed. The spaces within which the doubleness of the stimulus is not observed are called "sensory circles," though the figure 74 SENSUOUS LIFE. is not generally an exact circle. The smallness of the circle measures the perfection of the sensibility. The consciousness of mere contact, of tactual pressure, and, with some writers, that of temperature, comprise the feelings which should be grouped under touch proper. There are, also, a few other special modes of tactual sensation, such as tickling, and itch, which have a very well marked character of their own. Sensations of touch cannot be very vividly reproduced in imagination ; yet the reality of these representations is shown by our power of comparing a present sensation of touch, such as that of a brush or piece of silk, wdth a recollected experience, and also by the manner in which ideal sensations of touch are awakened by the visual appearance of objects. We seem io see the roughness, smoothness, or softness of objects, although, of course, these properties can only be apprehended by touch. This fact, too, marks the high degree of associability possessed by these sensations. These various qualities of the sense of touch give it great importance in the department of objective cognition. We have not, however, hitherto laid stress on the fact that pressure, revealed through tactual sensations, is an influential agent in the generation of our conviction of the externality of the material world, just as the apprehen- sion of co-existing points determines our assurance of its extension. In such sensations of pressure muscular feelings are often implied, and though passively received impressions of contact do really involve the apprehen- sion of something other than ourselves, yet it is when combined with the muscular sensations, and as con- sequent on the effort put forth by our own energy, that their full significance in the apprehension of the reality of the external world is realized. As a source of pleasure the sense of touch, apart from feelings of temperature and other organic states, ranks low. It has, however, been selected from the beginning as the sense most convenient for the intiiction of chastisement, and its capacity in this respect is indisputable. Active Touch. — The muscular or kinesthetic sensa- iions. — Sensations of pressure are commonly blended THE SENSES. 75 with muscular feelings of resistance on our part, and occasionally with those of movement. These feelings of impeded energy and of movement constitute the mani- festations of the so-called active or muscidav sense of modern pS3xhologists, and it is in connexion with these that the intellectual or cognitional importance of touch becomes most conspicuous. The difference between the tactual and muscular consciousness of pressure will be realized by holding up a half-pound weight on our hand, and then placing the same weight on our hand whilst the latter is supported by the table. In the former case there is in addition to the tactual impression a feeling described as a sense of effort or strain. Again, if we allow our arm to be unresistingly moved by another person, we shall have the passive consciousness of pressure or contact, with also faint tactual and organic feelings due to the changing position of the skin, joints, and muscles. But if we ourselves move it, instead of the passive feeling of pressure we have the consciousness of muscular energy put forth, accom- panied as before b}^ the faint organic and tactual sensations due to the varying position of the limb. Physiolog^ical Conditions. — The analysis of this state of consciousness and the determination of the physiological conditions of its various elements have given rise to the Muscular Sense Controversy, an unsettled dispute in which psychological, physiological, and pathological evidence is invoked on both sides. (i) One theory holds that our muscular consciousness consists merely of a special class of tactual sensations seated in ordinary afferent nerves in the skin and surface teguments, the crumpling, pressure, and strain of which excite these feelings, 'i'o this it is objected that in cases where the skin is rendered insensible by disease or anassihetics like cocain, the power of movement and the feeling of effort often remain. (2) The second theory includes among the elements of our muscular consciousness besides those of the skin, sensations located in sensory nerves pertaining to the muscles, tendons, ligaments, and cartilage connexions of the joints. All these feelings, it holds, are the concomitants of in-coming nervous processes along aff'erent nerves. They report and measure movement, strain, or resistance already accomplished, not 76 SENSUOUS LIFE. something to be done. Among the advocates of this view are W.James, Ferrier, Bastian, and Munsterberg. (3) The third theory maintains that in addition to, and quite distinct from these incoming or peripherally excited feelings, our muscular consciousness includes a feeling of innervation, oi effort put fortli, the mental correlate of centrally initiated outgoing currents of motor energy which traverse the efferent nerves in the execution of movement or resistance. Its chief supporters are Bain, Wundt, Ladd, Stout, and Baldwin. In behalf of (3) it is argued : {a) In children and young animals there is exhibited from the very beginning a fund ot activity and spontaneous movements originated by a surplus of energy rather than by external stimulation. The feeUngs attached to such primitive activity must have for their physical basis efferent or motor discharges. (Bain.) {b) A patient who strives to move a paralyzed limb is conscious of effort without any sensation of movement — which does not take place, (c) If the muscles which move the eye to right or left are partly paralyzed, the degree of rotation needed to fixate an object is over-estimated and its position misjudged. This illusion proves that our estimate of the movement is measured by the intensity of the effort or innervation which has to be exerted, not by incoming sensations of muscular contraction actually accomplished in the movement. (Wundt.) In favour of (2) it is urged by W. James : (a) The assumption of this unique active sense or feeling of innervation, opposed in nature to all other forms of sensation, — whicli are concomitants of afferent nervous processes — is ^'unnecessary.'''' This feeling, were it ever present, would have vanished as a useless link. Movements due to emotions and reflex action occur without it. {b) There is really no introspective evidence for its existence. An anticipatory image of the complex feeling of muscular contractions, involved in the movement plus the volition or fiat of the will — which is not a sensation — is the total mental state revealed by careful introspection. {c) To the arguments based on the seeming existence and our apparent estimate of the feeling of effort in cases of paralysis of certain muscles where incoming sensations from them would be impossible, it is answered that the feeling is still really of a purely afferent character coming from the strain of other groups of muscles, especially those of the chest and respiratory organs, as will be noticed if we "make believe" of shutting our fist tight, or puUing the trigger of a gun without really moving our fingers. We confess the question seems to us as yet not definitely decided. The reader will find it fully discussed in VV. James's THE SENSES. 77 Principles of Psychology, vol. ii. pp. 189 ff. 493 ff . ; and Ladd, Psychology Descriptive and Explanatory, pp. 115 ff. 218 ff. Cognitional value. — The discriminative sensibility of our muscular consciousness to varying degrees of resisting force is very delicate. The duration of muscular sensations is also finely felt. This latter property, when we have acquired the power of esti- mating velocity, is the chief instrument in our measure- ment of space. A sweep of the arm lasting for a longer or shorter time, velocity being equal, passes through a greater or less space. Estimation of velocity is not an original quality of muscular feeling, but is learned by experience. Velocity has no meaning unless in reference to space, and it is determined by th'j quantity of space traversed in a given time. We observe that, in a given time, a certain amount of energy is required to move the arm over a definite length of space, known by sight or touch. By association the degree of impetus becomes the symbol of the rate of velocity. The calculation of the quantity of movement executed by our limbs through means of the muscular feelings alone, unless in the case of a familiar act, is generally very imperfect. If we attempt to ascertain the size and shape of a strange room in the dark, we shall find how vague are our notions of our movement. Similarly, if the eyes are closed and the arm is bared so that the tactual sensa- tions of the sleeve are eliminated, the inadequacy of motor estimation of space will become apparent ; when the velocity is increased we invariably tmder- value the distance moved through.^ The muscular sensations, like the other organic feelings, cannot be vividly revived in imagination, but our power of determining the exact degree of ^ The fact that our muscular appreciation of velocity is not innate but acquired, and is at best vague and indefinite, constitutes a very serious difficulty to writers like Dr. Bain, who resolve our perception of space into the consciousness of unextended muscular sensations varying in duration and velocity. The latter idea involves the notions both of space and time, and should not be assumed as an innate endowment, least of all by the empirical school. (Cf. Mahaffy, The Critical Philosophy, pp. 138 — 144) ^S SENSUOUS LIFE. energy to be put forth in the practice of habitual ^ actions, such as standing, walking, writing, speaking, and the hke, is very dehcate. The sense of sight, just as well as that of contact, is a heavy debtor to these sensations. Not only the movements of the licad and the eyes, but the still more minute changes by which the convexity of the crystallme lens is niodified to suit the varying distance of the object, are all effected under the guidance and estimation of muscular sensations, and it is only by means of their acute sensibility that many of the nicest dis- criminations of the visual faculty are possible. Movement, moreover, enables us to multiply the experiences of each sense, to vary the relations between the object and the faculty, and to bring the most sensitive part of the latter to bear on the former. Consequently, the sensations which measure move- ment play an important part in perfecting our know- ledge of the properties of matter. Still it is the consciousness of foreign resistance revealed in tactual and muscular feelings combined, which forces upon us most irresistibly the reality of the external material world. In this respect the cognitional importance of the united muscular and tactual sense exceeds that of sight and all the other organic faculties together.^ Capacity for pleasure and pain.— l^he muscular feehngs may give rise to a good deal of pleasure or pain. When the body is in a healthy condition muscular exercise affords keen enjoyment, as is established by the general popularity of field sports. The proper pain of muscular sensations is fatigue, _ and this can l)e very severe when forced activity is maintained under exhausting conditions. Besides these mental states which we have described, the muscles, like other parts of the body, can be the subject of the pains of laceration or disease, but such feelings belong rather to the general group of organic sensations, " Amongst the qualities of matter made known by combined muscular and tactual sensations are solidity, shape, size., hardness, softness, elasticity, liquidity, &c. Consciousness of movement and of variation in pressure are the main factors in such perceptions. THE SENSES. 79 Hearing. — Physical and Physiological conditions. — This sense is aroused by vibratory movements transmitted from the sonorous substance through the air or other medium to the ear. The organ of hearing consists of three chief parts, the external ear including the pinna and external ineatns, the tympanic cavity, drum, or middle ear, and the labyrinth or internal ear. The two extremities of the tympanic cavity are connected by a chain of small bones, and the labyrinth consists chiefly of a number of small cavities, and contains a liquid in which the auditory nerve is distributed. The vibrations transmitted from the sounding object are concentrated by the external ear, and passed on through the middle ear by means of the chain of small bones to the liquid contained in the labyrinth. The disturbance of this substance excites the auditory nerve, and this excitation is the immediate ante- cedent of the sensation of sound. Musical Sounds. — Sensations of hearing naturally' divide into two great classes, those of musical, and those of non-musical sounds. Another important division is that into articulate sounds, or the words of language, and inarticulate sounds. When these last are non-musical they are called noises. The musical character of the first class of sounds seems to be dependent on the periodical nature of the vibrations which excite these sensations. The chief properties of musical notes besides intensity, are pitch, quality, and timbre or clang. The pitch of a sound means its altitude on the musical scale, and is determined by the rapidity of the vibration. 8o SENSUOUS LIFE. The terms timbre, clang, and sometimes musical quality, designate the pecuhar feature by which the sound of a note on one instrument differs from that iof the same note on another. Thus the timbre of the viohn differs from that of the cornet and of the human voice. ^^ Particular combinations of notes according to certain relations of pitch produce the agreeable effect known as harmony. Notes which sounded together produce instead an unpleasant sensation, are said to be discordant and inharmonious. Under certain circumstances, however, discords may be pleasant. Groupings of musical sound in particular time periods produce the consciousness of melody, and skilful combinations of various in- struments so as to secure harmony, melody, and agreeable blending of timbre conspire to awaken the delightful feelings of a rich symphony. Non-musical Sounds. — Of the non-muiical sounds the number which are classed as mere noises are practically unlimited. The collisions of different bodies, the cries of the various animals, the roaring of the wind and of the ocean, are instances of such. All forms of sound, both musical and non-musical, are susceptible of discrimination in regard to intensity and duration, as well as in regard to quality. It is owing to the very great delicacy of the ear in these several respects that articulate speech is an instrument of such enormous value. More than five successive excitations per second produce a ^'^ Helmholtz explains the different timbre of different instruments as due to variations in the upper tones which accompany the proper fundamental note. However, this theory cannot, as yet, be held to be established V, V THE SENSES. 8l continuous sensation in the eye, while the recupera- tive power of the auditory nerve is so perfect that we can distinguish sixteen impressions in the same length of time. The rapid succession of sensa- tions, frequently discriminated by but slight differ- ences in character and intensity, which present to us without fatigue the long series of syllables constituting a speech, exhibit the wonderful per- fection of this sense under these various aspects.^^ Sounds and Signs. — Sounds of all kinds are highly susceptible of being conserved in the memory and reproduced in imagination, and they are also readily associated with other mental states. To this latter property is due their aptness to constitute a system of symbols. The repeated conjunction of the sound of a name with the perception of its object causes the former to suggest in the mind of the child the idea of the latter. Later on, with the dawn of intellect and reflexion, words come to be used and recognized as signs of things. In acquiring a foreign language, the primary associations are formed, not, as in learning our mother-tongue, between the foreign words and the objects which they signify, but between the former and the corresponding terms in our own language, by the assistance of which we ordinarily think and reason about the objects of " A good musical ear is one that possesses a fine sensibility to pitch, to melodious groupings of successive tones, and to symphonic combinations of timbre. A good linguistic ear is one finely dis- criminative of the quality of sounds, and of the varying degrees of intensity which mark intonation or accent. As a consequence the two aptitudes are not always united. The ear well formed to catch the peculiar characteristics of the French, German, or Italian languages, may be insensible to considerable differences in pitch, and therefore unconscious of the discord effected by inharmonious com- binations. Perfection in either line implies good individual capacity of retention. Keen susceptibility to differences of pitch, and con- sequently to musical harmony, may be found where the general power of hearing is comparatively feeble, and vice versa. For a good linguistic ear, however, general acuteness of the sense seems requisite. 82 SENSUOUS LIFE. experience. In commencing to read the connexion is first formed between the visual sign and the oral syllable or word, though gradually the intermediate representation of the word tends to drop out of existence, and in the end tlie written symbol immediately suggests to us the object signified.^- Cognitional importance of Hearing. — Notwithstanding its very delicate sensibility as to differences in quality, intensity, and duration, in addition to the very revivable and associable character of its sensations, which all conspire to give the ear such high intellectual value as a representative faculty, it ranks very low as a direct medium of objective knowledge. Of itself it affords no information of the extension or impenetrability of bodies — the two fundamental properties of matter. Indeed, the attribute which it immediately reveals is of purely secondary and accidental character. Never- theless, of such a high order are the intrinsic excellences of its sensations, and so admirably are they adapted to compose a perfect system of signs, that, when once a few elementar}^ experiences have been gathered by the other senses, this faculty is enabled, by appro- priating them, to put us into a position to take possession of the rich treasures of knowledge acquired by the whole human race. Capacity for pleasure and pain. — The capacity of the ear for pleasure is large, while its potentialities for pain are comparatively limited. The agreeable feelings awakened by the qualities of musical sound are of the noblest and most refined character. They are rich in variety, they do not pall by long continuance, and they may be frequently renewed. In all these respects the}^ differ from the gratifications of the less refined senses. A far greater part, however, of these higher pleasures are traceable to intellectual and emotional enjoyment ^2 The muscular sensations excited in uttering words either aloud or in a whisper, make a parallel line of association with the aural and visual signs, and in persons in whom the faculty of articulation is more retentive, or more frequently exercised in acquisitions of this sort, thinking and reading in silence tend to be accompanied by movements of the lips. Energetic eftort to realize the full import of the visual sign occasions the same phenomenon. THE SENSES. 83 afforded by the general character of a musical com- position than to the mere sensuous satisfaction produced by pleasant sound. Cultivation increases the refine- ment and extends the range of this capacity for happiness, but at the same time rendering the faculty more keenly alive to defects and blemishes it anni- hilates many minor pleasures possible to the less delicate taste. Discord is painful to the musical ear, and harsh sounds of any kind, as well as intense noises, have an unpleasant effect on all normally endowed persons. Sight. — Physical and Physiological conditions. — The formal object of the eye is coloured surface. According to the now generally accepted undulatory theory, the physical conditions of sight consist of vibrations transmitted to the eye through the inter- vening ether from the reflecting or self-luminous body. Difference of colour depends on variation in the rate of rapidity of the vibratory movements. The organ of vision is an optical instrument of a very complicated and ingenious construction. The eye-ball is a nearly spherical body containing within it three masses of transparent liquid or gelatinous substances called humours, and so arranged as to form a compound lens. The shape of the eye-ball is secured by an outer coating called the sclerotic, which embraces the whole eye with the exception of the circular spot in front, where the transparent cornea takes its place. Under the sclerotic is a second covering, the dark choroid coat, and over the interior surface of this towards the back of the eye is distributed the retina. This is a transparent network composed of several layers of fibres and nerve cells, and connected with the choroid by a 84 SENSUOUS LIFE. layer of rods and cones. These latter seem to be the properly sensitive apparatus. In the centre of the retina is the yellow spot, which is the most sensitive part of the organ, and here the rods and cones are packed in greatest abundance. From the retina slightly to the side of the yellow spot the optic nerve proceeds to the brain. Rays falling on it are unperceived, whence it is styled the blind spot. Of the humours filling up the main body of the eye, the middle one, called the crystaUine lens, which is of double convex form, is the most important. The shape of this lens is capable of alteration, being rendered more or less convex by the automatic contraction or extension of the ciliary muscle to suit the distance of the object viewed. When something is presented to the eye, the rays passing from it enter the pupil of the eye and are con- centrated by the lens arrangements so as to form an inverted image on the retina. From the layer of rods and cones forming the inner stratum of the retina, this impression is conveyed as a neural tremor to the brain, whereupon the sensation is awakened. Sensations of Sight. — There are attached to the eye both muscular and visual sensations proper. The former, which measure the movement and the greater or less convexity of the eye-ball, contribute very much to the accurate determination of the special relations of visible objects. The visual sensations proper are those of light and of colour. These are susceptible of very delicate shades of difference, and the various hues of colour and THE SENSES. 85 degrees in the intensity of light which can be distinguished in a landscape are virtually innumer- able. It has been estimated by means of some ingenious experiments that an increase in the force of a stimulus equivalent to about one in one hundred can, within certain limits, be just discerned by the eye. The principal species of colour generally recognized are the seven hues of the spectrum, red, orange, yellow, green, blue, indigo, and violet. There are a large number of distinguishable inter- mediate tints between these leading colours, and the terms have therefore not a very exactly defined meaning. These various hues are found to result from the analysis of white light. The ether vibra- tions which excite visual sensations are of enormous rapidity, and the rate increases from about 460 billions per second, for red rays, to about 670 billions in the case of violet. Helmholtz and others have traced analogies between the colour spectrum and the musical scale. In point of agree- ment we find {a) a series of seven principal colours, in corre- spondence with the notes of the gamut, {b) both series produced by variations in the rate of the vibratory stimulus, and {c) both capable of certain agreeable and disagreeable combinations described as harmonious and inharmonious. The points of difference are however greater, {a) The character of each of the tones of the musical octave is so distinct and well marked as to have been recognized from the earliest times ; the colours of the spectrum on the contrary are vaguely defined and pass gradually into each other, many intermediate hues having equally good claims to a recognition in the scheme ; {b) the change in the musical octave advances regularly in one direction, each succeeding note being farther from the first, while in the spectrum the movement is along a curve, and the last colour, violet, returns nearer than either indigo or blue, to the earlier colours red and orange ; (c) the auditory sensation rises regularly with equal increments in the rate of vibration, whilst large changes produce no 86 SENSUOUS LIFE. conscious effect in parts of the spectrum ; (d) the range of vision is exhausted by a single octave, while the ear can span from six to eight. Composite Sensations.— PAthough. the sensation of white is evoked by a combination of physical stimuli separately productive of other feelings, it is inaccurate, as we have before indicated, to speak of the consciousness of white as being a compound or complex mental state. The sensation, in itself unanalyzable, must be accepted as such.^ The true type of the compound or complex sensation is that aroused by a union of different voices or instruments, where attention enables us to discriminate the separate elements of consciousness. The analysis of white light, the existence of various forms of colour blindness, of colour harmony, and of what are called iiegative^^ images, have suggested the hypothesis that the nerves of vision distributed in the retina are of certain different classes adapted to respond to particular elementary forms of colour. The theory has assumed different forms in the hands of different scientists, but as the question is physiological rather than psychological, w^e need not enter into it here.^* Tone and Depth. — The term tone is sometimes used to express the position of a colour in the spectrum, while depth is dependent on the quantity of pure white light '^'•' After-mages, incidental images, or spectra, are of two kinds, positive and negative. The former term is used to denote the images of sensuous perceptions of objects, which frequently continue to persist for some brief time after the cessation of the stimulus. If after gazing steadily for a few minutes at a coloured object we direct our eyes to a white surface, instead of the positive after-image we become conscious of an image of the object, but in the complementary hue. This is termed a negative image, and is explained on the above hypothesis as due to the temporary fatigue and consequent obtuseness of the nerves previously excited, which are now unable to absorb their share of the new stimulus. ^* The survival of these after-images was observed by Aristotle and the Scholastics: "Si aliquis videt aliquid lucidum ut solem, et subito claudat oculos, non advertendo visum, sed observando illud directe, primo apparebit ei color rei splendidae deinde muta- bitur in medics colores successive donee veniat ad nigrum, et omnino evanescat et hoc non continget nisi propter simulacra splendid! derelicti in visu." (St. Thomas, Comm. Dc Somuiis, lect. 2.) THE SENSES. 87 blended with the colour in question. The word intensity is occasionally employed as synonymous with depth; properly, however, it should signify the stronger or feebler force of the sensation. In addition to the fineness of the discriminative power of sight in these several respects, visual sensations are in a high degree capable of being retained in memory and recalled in imagination. In fact, so superior in vivacity are the representations of this faculty to those of the other senses, that some writers have been found to deny, but without adequate grounds, the existence of any other kind of images. The eye, though surpassing the other senses, is less delicately sensible to the duration of the stimulus than the ear. The persistence of positive after-images exhibited in the continuous im- pressions produced by the rapid circular movement of a bright object, prevents us from discerning more than five or six successive excitations in the second. Cognitional importance. — These numerous capabilities would be sufficient of themselves to secure to sight high cognitional rank, but it is to the fact that the eye aftbrds an immediate presentation of surface extension^ that its fundamental importance as a source of objective knowledge is due. The apprehension of colour neces- sarily involves that of space in two dimensions. It is undoubtedly true that originally the single eye, if it remained in a fixed position, could have apprehended but a very limited quantity of surface, that its precep- tion of shape would have been extremely vague, and that it could have afforded no information at all as regards distance; but nevertheless the sensation of colour necessarily implies some perception of extension. The point will be made clearer when we come to treat of the development of sense-perception ; here, however, we would note that the means by which our visual perceptions of shape and distance are elaborated, and our apprehension of surface enlarged, are changes in the position and form of the eye made known to us by muscular sensations. The movement of the axis of the eye round the object viewed, the convergence of the two eyes varying with its distance, the self-adjusting 88 SENSUOUS LIFE. process by which the optical lens is flattened or rendered more convex so as to focus the object upon the retina, are accompanied by faint feelings of tension which play an important part in giving precision to our spatial cognitions. In mature life the "local" sensibility of the retina is very fine. Close to the centre of the yellow spot irritations as near together as •004 mm. are felt as distinct ; but the discriminative power diminishes as we pass towards the circum- ference. The size of the retinal image, of course, decreases with the distance of the object, still this extreme delicacy of the retina to the local character of the irritation enables the eye to become a very perfect instrument for the accurate appreciation of extension. Capacity for pleasure and pain. — As a direct source of pleasure or pain visual sensations rank probably lower than those of any other faculty, though indirectly they may contribute much to our happiness. Bright lights and hues are pleasing, and harmonious combinations have an agreeable effect. A strong glare of light is painful, but the feeling is organic rather than visual. Prolonged confinement in the dark produces an intense desire for light and great joy on first restoration to liberty, but the pleasure soon fades. The contempla- tion of the beauties of nature and art affords rich and refined delight, but here the effect is of an intellectual and emotional character, and not merely an immediate function of the sense. The Senses compared. — In our last chapter we remarked on the inverse ratio subsisting between the perceptional and the pleasurable or painful capacity of the senses. Glancing back at them now, when they have been separately passed under review, and their chief features described in detail, the truth of that observation will be realized. If we divide our tactual consciousness into the two great groups, the organic sensations, including the feelings of temperature on the one side, and the muscular feelings and sensations of touch proper on the other, and proceed to arrange them first according to emotional, and then in regard THE SENSES. 89 to cognitional rank, we shall find that the two schemes will assume virtually an inverse order. Viewed as direct sources of pleasure and pain, starting from the highest they seem to stand thus : organic sensation, taste, smell, hearing, muscular and tactual states, and sight. But marshalled as instruments of objective knowledge the order is reversed : sight, tactual and muscular sensations, hearing, smell, taste, and lowest, the organic feelings. This classification regards only the immediate or direct emotional and cognitional properties of the consciousness of each sense, and the intrinsic difficulties of all such comparison would pro- bably cause diversity of view about the former scheme ; still, estimated from this limited standpoint, it seems to us approximately correct. Indirectly, indeed, sight is a much more important source of pleasure and pain than the sense of smell, and the knowledge of the universe acquired by hearing far exceeds that gathered from the actual experience of all our other senses combined ; but in both cases we have merely appropriation of the results attained by the other faculties, and extension of these results by means of association and inference. Viewed purely as a state of feeling, a sensation of colour or sound can afford much less pleasure or pain than an agreeable odour, or a nauseous stench. Similarly, the sensations of hearing are more precise, more finely discriminable, and more vividly revived in imagination, not only than those of taste and smell, but even than our tactual and muscular consciousness. Yet, inasmuch as they give us immediately no assurance of the reality, or of the extension of the material world, they must be ranked cognitionally higher than taste or smell, but lower than the combined muscular and tactual sense. Touch, indeed, since it reveals the mechanical properties of the world, has claims to stand even before sight as an instrument of objective cognition, and it is certainly more necessary ; still, the immense range of the latter faculty, its perfect presentation of the geometrical relations of the universe, and the delicacy of its other cognitive capabilities have led us to place it at the head go SENSUOUS LIFE. of the list. We need not attempt any further justifica- tion of the arrangement adopted, as the reader, by returning on our treatment of the senses separately, may ascertain the various considerations which have led to our conclusion. ^^ The ♦' Law of Relativity."— The quality and intensity of a sensation are affected not only by the character of its own stimulus, but also by the quality and intensity of other simul- taneous or immediately preceding sensations. Thus the same water is apprehended as hot or cold if the hand has been previously dipped in a liquid of lower or higher temperature. The same article may feel smooth or rough, heavy or light, according to the opposite character of the previous experience. After tasting a bitter substance water appears sweet. The sudden cessation of a prolonged noise has a startling effect, as when the miller is awakened by the stopping of his mill. A black object produces a stronger impression when seen after or in the midst of a white field, and the several colours are felt more deeply " saturated," that is, come out richer and fuller when observed at the same time or immediately subsequent to those of complementary hue. In general contrast, whether simultaneous or successive, intensifies the force of sensation. On the other hand, the effect of protracted stimulation of a sense diminishes and may finally cease to be noticed. We are ordinarily unconscious of the contact of our clothes, of the pressure of our own weight upon our limbs, of the continuous hum of the city, of the smell of flowers, or of the oppressiveness of the atmosphere in a room where we have been for some time, and, speaking generally, of any constant uniform excitant. This influence of variation upon consciousness has been called by recent psychologists the " Relativity of Sensation." It is a well-known experience in our mental life, and a consi- derable factor in our pleasures and pains. It was familiar to Aristotle and the Schoolmen, who, on account of its effects, laid down the rule that to secure correct apprehension the '•''' Balmez, Fundamental Philosophy, Bk. II. cc. x. xi. maintains the inferiority of touch to sight and hearing from a cognitional point of view. He does not, however, distinguish sufficiently in this question between the direct or immediate efficacy of a sense and that which is merely mediate. In range and representative power the more refined senses vastly surpass touch, but to a very large extent their wealth is built upon the capital supplied by the more fundamental faculty. THE SENSES. qi several sensuous faculties must be in a neutral or normal condition.^*"' But the sweeping generalization erected upon these facts under the title of the Law of Relativity is untenable. Accord- ing to this doctrine, at least as expounded by some of its best- known advocates, all consciousness is merely /^^//;i^ of difference or change. Thus Hobbes asserted that " to be always sensible of one and the same thing is the same as not to feel at all." Dr. Bain writes : " The Principle of Relativity, or the neces- sity of change in order to our being conscious, is the ground- work of Thought, Intellect, and Knowledge as well as Feeling. . . . We know heat only in the transition from cold and vice versa. . . . We do not know any one thing in itself, hut only the difference between it and another thing. . . . The present sensa- tion of heat is in fact a difference from the preceding cold."^'' Criticism. — To us it seems clear that whilst change — ■ motiis de potentia ad actum, as the scholastics termed it — is an essential element in the aivakening of sensation, and also an important factor in its vividness, it is, nevertheless, the very reverse of the truth to assert that all consciousness is a "feeling of difference." In sensation we are primarily conscious of a positive quality, for instance, of a sound or of a colour, not merely of the relation between two feelings. All comparison presupposes the perception of the terms to be compared, and the primitive act of the sense is not com- parative, but simply apprehensive. What man's conscious- ness would be like if he always had but one imvarying form of sensation we do not pretend to know ; but experience shows that we may continue aware of a uniform stimulus, for example, of a musical note for an indefinite time if it be not submerged or crowded out by other feelings,^^ ^♦^ " Sicut tepidum in comparatione ad calidum est frigidum; in comparatione ad frigidum est calidum. . . . Et oportet quod sicut organum quod debet sentire album et nigrum neiitrum ipsorum hahet actii sed utrumque in potentia; et eodem modo in aliis sensibus." (St. Thomas, De Anima, Lib. ii. lect. 23. Cf. also Dc Somniis, lect. 2.) ^^ Cf. Senses and Intellect, p. 321 ; Emotions and IVill, p. 550 ; Body and Mind, p. 8i ; also Hoffding, Outlines, pp. 114 — 117, and Wundt, op. cit. pp. Ill — iig. ^^ Mr. J.Ward has forcibly argued against the supposed law: (i) That the axiom, Idem semper sentire et non sentire ad idem recidiint, though a truism in reference to the totality of mental life, or to con- sciousness as a whole, is false as regards many individual impressions. (2) That the suggested illustrations, e.g., insensibility to continuous motion, temperature, pressure of the air, &c., are cases of physio- logical, not psychical habituation, and so are not constant mental impressions at all. (3) That " constant impressions" in the form 92 SENSUOUS LIFE. \ The actual facts on which the " Law of Relativity " and *' Law of Contrast " are based seem to receive a simple physiological explanation in the enfeebling effect of fatigue upon the sense-organ and nerves engaged. These latter become habituated to the stimulus, and react with less energy if the same excitation be prolonged, whilst contrasted feelings employ fresh neural elements or other cerebral tracts. Moreover, from the mental side uniform sensation diminishes in interest, and attention being drawn away by rival novel stimuli, the m.onotonous experience attracts less and less notice. The Relativity of Knowledge. — There is another form of the doctrine of the relativity of consciousness, which maintains that all our knowledge is relative to us, and that we have accordingly no real knowledge of things outside of the mind. This latter question will be discussed more appropriately after we have dealt with sense-perception, and we shall treat it under the title of the Relativity of Knowledge at the end of chapter vii. Both doctrines are erroneous, but many writers maintain the second without adhering to the first, although those who adopt the first naturally adhere also to the second. The Scholastic Doctrine of the Internal Senses. — In addition to those sensuous faculties by which we are enabled to perceive external objects, the mind is endowed with the capability of apprehending in a sensuous manner, facts of a subjective order. This power or group of powers constitutes those modes of mental life styled by the schoolmen the Internal Senses. The Aristotelian doctrine elaborated by the mediaeval thinkers distinguishes four such faculties, the sensiis communis, the vis cestimativa or vis cogitativa, the imagination, and the sensuous memory. They were termed senses, or organic powers, of "fixed ideas" are the very reverse of a "blank." (4) That if every feeling were " two-fold " or a " transition," a man surrounded by a blue sky and ocean, or passing from a neutral to a positive state of consciousness, must be unaware of any impression at all, which is not the fact. (5) There is, too, the old difficulty of Buridan's ass. (6) Moreover differences, which are themselves real presentations or objects of apprehension, are cognized, e.g., degrees of variation in shade, pitch, pressure, &c., and therefore presuppose the perception of the absolute terms. Mr. Ward also rightly traces Dr. Bain's confusion on this subject to his ignoring the difference between the mere successive or simultaneous occurrence of two related feelings, and the intellectual perception of their relation. {" Psychology," Encycl. Brit. Qlh Edit. See also Mark Baldwin, Senses and Intellect, pp. 58—61 ; W. James, Vol. II. pp. G — 20; and Farges, VObjectivitc de la Perception, pp. 104 — 115, 202 — 208.) THE SENSES. 93 because they operate by means of a material organ, and have for their formal objects individual, concrete, sensuous facts. The word internal marks their subjective character, and the internal situation of the physical machinery of their operations. Sensus Communis. — The sensus communis, or common sense, has also been styled the internal sense and the central sense. It has been described by St. Thomas, after Aristotle, as at once the source and the terminus of the special senses. By this faculty we are conscious of the operations of the external sensuous faculties, and we are made aware of differences between them, though we cannot by its means cognize them as different. Apart then from intellect, by which we formally compare and discriminate between objects, some central sense or internal form of sensibility is required, both in the case of man and of the lower animals, to account for the complete working of sensuous life. In the growth and development of sense-perception, the action of this internal form of sensuous consciousness is involved. Antecedent to and independent of intellectual activity, the revelations of the several senses must be combined by some central faculty of the sensuous order, and it is this interior aptitude which has been called sensus communis-}^ Vis Aistimativa. — The vis cestimativa, or sensuous judicial faculty, was a name attributed to those complex forms of sensuous activity by which an object is apprehended as fit or unfit to satisfy the needs of animal nature. It thus denotes that capability in the lower animals which is commonly described as Instinct. The term vis cogitativa was sometimes 19 It has been held by St. Augustine, St. Thomas (of. Sum. i. q. 78, a. 4. ad 2. and 87. 3. 3), and other philosophers, that no sense can know its own states, and that, not merely for the co- ordination of the different senses, but for the cognition of any single sensation, an internal faculty in addition to the special sense is requisite. Aristotle {De Anima, III. 1. 2) decides against this view on the intelligible ground that such a doctrine would involve an infinite series of sensuous faculties. Elsewhere, however [De Somno et Vigilia, 1. 2), he appears to adopt the contrary theory. Suarez argues cogently against this multiplication of faculties as unneces- sary, and his teaching appears to us sound. No sense can have a reflex knowledge of its own states, but this does not prevent a sense from having concomitantly with the apprehension of something affecting it an implicit consciousness of its own modifications. A being endowed with the sense of touch or hearing ought to be con- scious, it would seem, of tactual or auditory sensations without the instrumentality of any additional faculty. (Cf. Suarez, De Anifna, Lib. III. c. ii. and Lahousse, op. cit. pp. 160 — 163.) 94 SENSUOUS LIFE. employed to designate the aptitude for analogous operations in man, at other times to signify a certain mode of internal sensibility operating concurrently with the intellect in the perception of individual objects.-" Sentimento Fondamentale. — The term sentimcnto fonda- mentale, or fundamental feeling, was employed by Rosmini to denote an assumed faculty, or form of sensuous consciousness, by which the soul is continually cognizant of the body in which it is present.'^^ The soul, he teaches, and not the living being composed of both soul and body, is the true principle of this feeling. It is by their modification of the sentimento fonda- vientale ihdii the impressions of the special senses reveal them- selves to the soul. The fundamental feeling, unlike the sensiis communis of the scholastics, is held to have been ever in a condition of activity, even antecedent to the exercise of the special senses. " It begins with our life, and goes on con- tinuously to the end of it." Nevertheless, it is rarely adverted to, and considerable power of psychological reflection may be required to discover its existence. By this feeling we have a subjective perception of our organism ; through sight and touch, on the other hand, we apprehend it in an extra-subjective manner. Finally, the union of soul and body consists in an immanent perception of the activity of this faculty. Sensus Fundamentalis. — Tongiorgi uses the terni senstis fundamentalis in a kindred meaning to denote an inferior form of the sensus intimus. By the sensus intimus, he understands a perpetual consciousness both of its own substantial existence and of its acts, with which he maintains the soul to be endowed. This actual cognizance of itself is essential to the 20 It was urged that intellect, the formal object of which is the miiversal, cannot directly apprehend individual substances as such. Nevertheless, we have intellectual knowledge of them, for we form singular judgments, e.g. : " This plant is a rose," " Peter is a negro." Consequently, it was inferred, there is a special form of internal sensibility through which the concrete object is so apprehended that by reflection upon this sensuous presentation the intellect can cognize the singular nature of the object. St. Thomas thus describes the operation : " Anima conjuncta corpori per intellectum cognoscit singulare, non quidem directe, sed per quandam reflexionem, in quantum soil, ex hoc, quod apprehendit suum intelligibile, revertitur ad considerandum suum actum et speciem intelligibilem, quas est principium ejus operationis, et ejus specie! originem, et sic venit in considerationem phantasmatum et singularium quorum sunt phantasmata. Sed hac rejiexio compleri non potest, nisi per adjunctionem virtutis cogitative et imaginative." {Q. Un. de Anima, a. 20. ad i.) 21 ''By the fundamental feeling of life we feel all the sensitive parts of our body." (77*^; Origin of Ideas, Eng. Trans. § 705.) THE SENSES. 95 soul and independent of all special mental modifications. It is, moreover, natura if not tempore antecedent to them; yet, as the soul exists always in some particular state, it can never apprehend itself unless as determined by an individual affection. The sensus intimus exerts itself in a higher and a lower form, as rational, and as sensuous consciousness. By the inferior order of activity the soul continuously feels its presence in the body which it informs, and thus apprehends the various impressions which occur in different parts of the organism. This sensuous cognizance of the body he styles the sensus fundamentalis, inasmuch as it is the common root or principle of the external senses,- Suarez' doctrine. — Accepting the doctrine of Suarez, that there is neither a real, nor formal distinction between the internal senses, it does not appear to us to be of any very profound importance what classification of faculties we select, as best fitted to mark off the various phases of mental life which have been allotted to internal sensibility. Moreover, the brain seems to be the common physical basis for all these different modes of consciousness, so that there is no differentia- tion of organ corresponding to special operations which might tell decisively in favour of any particular scheme of division. Internal Sense. — The term internal sense has had a variety of significations in the history of Philosophy. In the Peri- patetic system, sensus internus designated generically the four faculties, sensus communis, vis cestimativa vel cogitativa,phantasia, a.nd memoria sensitativa ; but also at times it indicated more specifically the sensus communis. In the Cartesian school, the sensus intimus or conscientia, signified all consciousness of our own states, whether sensuous or intellectual ; and the latter -^ St. Thomas applies the term sensus fundamentalis to the faculty of touch. The sensus fundamentalis, as described by Rosmini and Tongiorgi, has been objected to by modern scholastic writers on various grounds, (i) Internal sensibility, since it is an organic faculty apprehending concrete sensuous facts, must, like external sense, pertain not to the soul alone, but to the whole being — the composituni humannm. (2) The primary function of internal sense is the apprehension of the modifications of the external senses, its exercise must thus follow, and not anticipate, that of the latter. (3) There is absolutely no evidence for the existence of a perpetual cognition of our own body independent of all special activities. (4) The constitution of the union of body and soul in the perception of the former by the latter would reduce their connection to that of an accidental alliance. (Cf. Liberatore, On Universals, Trans, by E. Dering, pp. 130, seq., also PsycJwlogia, §§ 27 — 29; Lahousse, Psych. %% 348 — 355. Contra: Tongiorgi, Psych. 271, 280; Rosmini, The Origin of Ideas, Vol. II. Ft. V. c. iii., and Psychology, Eng. Trans. Bk. I. c. vii.) ij 96 SENSUOUS LIFE. term has retained the same connotation with modern scholastic writers.--^ With Locke, internal sense is equivalent to the intel- lectual faculty of reflection, by which our mental states are observed. With Kant, it comprises the sensuous intuition of our mental states, not, however, as they are in themselves, but as modified by the a priori form of time. The term internal sense, legitimate in its original signification in the Peripatetic system, is very inappropriate in its modern usage as expressing the intellectual activity of self-consciousness. That activity is neither in point of object, of nature, nor of intrinsic dependence on physical organ akin to the senses. Basis of Division. — The scholastic classification of four internal senses was grounded on the existence of generic differences in the formal objects o£ the several faculties. The formal object of the sensiis communis consists of the actual operations of the external senses ; that of the imagination is the representation of what is absent ; the function of the vis (Bstimativa is the apprehension of an object as remotely suitable or noxious to the well-being of the animal ; that of the sensitive memory is the cognition of past sensuous experi- ences. Some writers reduced these faculties to two, others augmented them to six. The nature of the distinction between these senses was also disputed. Suarez,^* after a careful examination of the various opinions on the point, decides against the existence of either a real or a /or;;m/ distinction, and contends that Aristotle is with him in looking on the internal senses as merely diverse aspects or phases of a single sensuous facult3\^-^ Common Sense. — Common sense is also a very ambiguous term, (i) In the Aristotelian Psychology, it meant only the internal sense above described. (2) It has been since used to express certain universal and fundamental convictions of mankind. It is in this signification that it has been appealed to as a philosophical criterion of truth by the Scotch school. (3) In ordinary language it implies good sense, sound practical judgment. (4) Common sensibility, and also common sense, have been sometimes used by psychologists to indicate {a) the faculty of touch, and {b) the ccenassthesis or the vital sense, and the various forms of organic sensibility. Readings. — On classification of the senses, cf. St. Thomas, Sj