rtos^ JJtnJ Book Sj'f CoipghtlJ?. COPyRIGHT DEPOSIT. INTRODUCTION TO PSYCHOLOGICAL THEORY BY BOEDEN P. BOWNE PROFESSOR OF PHILOSOPHY IX BOSTON UNIVERSITY AUTHOR OF "metaphysics" NEW YORK HARPER & BROTHERS, FRANKLIN SQUARE 1887 ^^%' Copyright, 1886, by Harper & Brothers. All rights reserved. PREFACE, The aim of this work is given in its title. First, it is an " introduction " only, and does not go into the details or the literature of the subject. The aim is to point out the highways of psychology, rather than its myriad by- ways. Secondly, it is an " introduction to psychological theory," and aims less at a knowledge of facts than at an understanding of principles. Until principles are set- tled there is no bar to the most fantastic theories and interpretations. These principles being illustrated in the most common facts of experience, it is not necessary to psychological insight to make an anthology of madhouse and hospital stories. Such a procedure has about the same relation to psychology that the various books of " wonders " or the " brilliant experiments " of the popular lecturer have to sober physical science. An odor of quackery is percep- tible in both cases. The plan of the work precludes much attention to physi- ological psychology. Whatever the merits of this science may be, it presupposes pure psychology. If our aim is to give a physiological explanation of psychological facts, VI PKEFACE. we must first know the facts. Or if our aim is the more modest one of finding the physical conditions or attend- ants of mental facts, again we must know the facts. But this knowledge is not possible by the way of physiology, and in any case the mental facts remain what they al- ways were. Their likenesses and differences and essential nature would not be changed if physiology were supreme. Even the " new psychology " would not give us new men- tal facts, but only a new interpretation of the old facts. The Zeitgeist itself begins at last to see this ; and the naive onslaughts on the " old psychology " are happily growing fewer. Psychological literature shows very marked progress in this respect within the last twenty years. Physiology remains a most estimable science, but the physiological reconstruction of psychology has been postponed. The study of the physical conditions of our mental life has a pathological and practical importance; but it does not promise any valuable psychological results, at least for those who can distinguish between the physi- cal conditions and the mental facts which they condition. The limitation of plan involves many omissions ; and in these there will seem to be a measure of arbitrariness. Hence many will not find here what they want, and proba- bly still more will find what they do not want. There seems to be no way of adjusting so grave a difficulty except by maintaining, on the one hand, freedom to pub- lish, and, on the other, freedom not to read. Borden P. Bowne. Boston, September, 1886. CONTENTS. INTRODUCTION. Definition of Psychology, p. 1. — Possible Directions of Psychological Study, p. 1. — Psychology mainly an Introspective Science, p. 2. — Objections to the Introspective Method, p. 3. — Reasons for the slow ^ Growth of Psychology, p. 4. PART I THE FACTORS OF THE MENTAL LIFE. Chapter L, the subject of the mental life ... 11 Reality of Self the Condition of the Mental Life, p. 11. — Objections considered, p. 11. — Impossibility of Rational Consciousness apart from an Abiding Self, p. 12. — A Word on Method, p. 14. — Defini- tion of Materialism, p. 15. — Materialism unclear in its Meaning, p. 16. — Ambiguity of the Facts of Mental Dependence, p. 18. — Difiiculties of Materialism, p. 19. — Hylozoistic Materialism, p. 21. — Relation of Hylozoism to Physics, p. 22. — Untenability of Hylo- zoistic Materialism, p. 25. — Bearing of Materialism on Life and Action, p. 30. — Bearing of Materialism on Knowledge, p. 31. — Scepticism involved in Materialism, p. 34. — Man a Dual Being, p. 36. —Value of this View, p. 36. Viu CONTENTS. Chapter II. PA6S SENSATION 39 Physical Conditions of Sensation, p. 40. — Sensation not explained by its Physical Conditions, p. 40. — Forms of Nervous Stimulus, p. 41. — Attempts to explain Differences of Sensation, p. 43. — Our Igno- rance of Nervous Action no Psychological Loss, p. 48. — Kelation of Sensation to Stimulus, p. 49. — Weber's Facts and Fechner's Theory, p. 50. — Difficulties of Fechner's Law, j). 52. — Interpretations of Fechner's Law, p. 53. — Differences in Simple Sensations, p. 56. — Double Aspect of Sensations, p. 58. — Organic Sensations, p. 59. — Source of the Sensations arising from Motion, p. 59. — Arguments for Sub-conscious Sensations, p. 62. — Criticism of the Same, p. 65. — Simplicity of Sensations, p. 69. — Unclearness of the Doctrine, p. 70. Chapter III. THE mechanism OF REPRODUCTION. ... 73 Facts of Reproduction, p. 73. — Two Classes of Theories, p. 75. — Her- bart's Theory, p. 76. — Ambiguity and Difficulties of Herbart's Theory, p. 77. — Uncertainty of the English Associationalists, p. 82. — Physiological Theories of Reproduction, p. 83. — Shortcomings of all Cerebral Theories, p. 84. — Failure of every Theory to give a true Insight, p. 86. — Statement of Results, p. 87. — Laws of Association, J). 90. — The Laws criticised, p. 90. — Sub-conscious Association, p. 96. Appendix to Chapter III. CEREBRAL THEORY OF REPRODUCTION ... 99 Forms and Implications of the Theory, p. 99. — Complexity of the Cell Theory, p. 101. Difficulty of keeping Impressions separated, p. 104. — Obscurity of the Theory on Important Points, p. 105. — No Account given of Actual Association, p. 107. — Physiological Difficulties, p. 109. — Habit Form of the Cerebral Theorj^ p. 111. — Difficulties of this View, p. 112. — Sense in which the Brain is the Organ of Memory, p. 113. CONTENTS. IX Chapter TV. PAOB THE THOUGHT FACTOR 115 The Two Schools of Psychology, p. 115. — Psychological and Philo- sophical Aspect of their Diti'erences, p. 116. — Primal Shortcoming of Sensationalism, p. 118. — Judgments cannot arise through Asso- ciation alone, p. 119. — Two Distinct Processes in the Mental Life, p. 121. — Ambiguity in the Facts of Mental Development overlooked by Sensationalists, p. 123. — The Categories, p. 126. — Time, p. 127. — Time not a Quality of Mental States, nor an Abstraction from them, p. 128. — The Sequence of Ideas not the Idea of Sequence, p. 128. — Memory not the Source of the Idea, p. 129. — The Idea of Time not dependent on the Idea of Causation, p. 131. — Fundamen- tally, Time is a Law of Mental Synthesis, p. 131. — Space, p. 133. — Different Views of Space, p. 133. — Associational View, p. 134. — Ambiguity and Untenability of this View, p. 135. — Superficiality of the Common View, p. 143. — The Idea of Space not explained by the Extension of the Nerves or by the Extension of the Soul, p. 144. — The Source of the Idea must be sought for in the Nature of the Mind, p. 148. — Space essentially a Law of Mental Synthesis, p. 149. — The Unity and Infinity of Space a Consequence of this Law, p. 149. — Relation of Sense Experience to the Idea, p. 151. — iV-dimen- sional Space, p. 151. — Number, p. 153. — Number purely a Mental Product, p. 153. — Failure of the Attempts to deduce it from Sense Experience, p. 154. — Number as the Science of Pure Time, p. 156. — Substance, p. 158. — This Idea not derived from the Senses, p. 158. — Sensationalist Doctrine of Substance, p. 160. — Criticism of the Same, p. 160. — Cause, p. 165. — Criticism of the Sensational Theory, p. 167. — Claim that the Idea of Causation arises only from our Volitional Activity, p. 171. — The Truth in this Claim, p. 172. Appendix to Chapter 1Y 175 Attempt to found Sensationalism on the Experience of the Race, p. 175. — Mutual Opposition of Sensationalism and Materialism, p. 175. — Difficulty of connecting the Experience of the Individual with that of the Race, p. 178. — Heredity the Problem, not its Solution, p. 178. — Ambiguity of the Facts, p. 178. — Inability of Heredity to create New Ideas, p. 180. — Mechanical Nature of the Doctrine, p. 180. X CONTENTS. Chapter Y. PAGE THE FEELINGS 182 Feeling undefinable, p. 182. — Feeling cannot be deduced, p. 183. — Feeling cannot be understood through its Conditions, p. 186. — Physical Feelings, p. 188. — Obscurity of the Nervous Processes which condition them, p. 189. — No satisfactory Classification of the Feelings which have only a Mental Source, p. 191. — Mental Feelings as Functional, p. 191. — Emptiness of this Conception when made Universal, p. 193. —The Ego Feelings, p. 193. —Dependence of Feeling on its Relation to Self-consciousness, p. 194. — The Social Feelings, p. 195. — Attempts to deduce them from Selfish Feeling, p. 195. — Relation of the Ego Feelings to Social Relations, p. 197. — ^Esthetic Feeling, p. 198. — iEsthetic Judgments founded on iEsthetic Feeling, p. 198. — Various Forms of ^Esthetic Feeling, p. 199. — Significance of Association for Esthetics, p. 200. — Reasons for the Diversity of Esthetic Judgments, p. 201. — "Why do Objects please us sesthetically ? p. 201. — Insufficiency of Physio- logical Explanations, p. 202. — Failure of Attempts to base ^Esthetics on a Single Principle, p. 203. — Uncertainty of the Boundaries of the Esthetic Realm, p. 204. — The Moral Feelings, p. 205. — Two Directions of Ethical Study, p. 206. — The basal Ethical Fact, p. 206. — Double Standard of Ethical Judgment, p. 207. — Deduc- tions and Reductions of the Moral Sentiments, p. 209. — Religious Feeling, p. 210. — Theories of the same, p. 211. — The Desires, p. 214. — The Object of Desire, p. 214. — Pleasures not Commen- surable, p. 215. — Direction and Control of Feeling, p. 216. — Chapter VI. WILL AND action 219 Not all Activity is Volitional, p. 220. — Constitutional Activitj^ p. 220. • — Volition indefinable, p. 221. — Volition distinguished from its Psychological Attendants, p. 221. — Volition implies Consciousness, p. 222. — In Spontaneous Thought Volition regarded as Free, p. 222. — What this Freedom means, p. 223. — Opposing Conceptions, p. . 223. — Determinism not founded on Consciousness, p. 225. — Bearing of the same on Action and Knowledge, p. 226. — Reasons for Determinism, p. 228. — The Problem speculatively insoluble, CONTENTS. XI PAGE p. 230. — Various Misunderstandings, p. 231. — Freedom implied as a Condition of Rational and Social Life, p. 232. — Limitation of Freedom, p. 233. Chapter YII. CONSCIOUSNESS AND SELF-CONSCIOUSNESS . . 235 Definitions of Consciousness tautologous, p. 235. — Traditional Con- fusion, p. 235. — Consciousness not a Faculty, p. 237. — Antithesis of Subject and Object the Universal Form of Consciousness, p. 238. — Objections by Sensationalism, p. 238. — Varying Degrees of Con- sciousness, p. 239. — Consciousness dependent on Thought as well as on the Sensibility, p. 241. — Misunderstanding of the Antithesis of Subject and Object, p. 242. — The two Factors of Self-consciousness, p. 244. — The Conception of Self not an Experience of Self, p. 245. — Self-experience admits of no Deduction, p. 246. — Development of Self-experience into Self-knowledge, p. 248. PART II. THE FACTORS IN COMBINATION. Chapter I. PERCEPTION 253 Perception a Complex Process, p. 253. — Perception a Reaction of the Mind against External Action, p. 254. — This External Action no Copy of the Object, p. 255. — This Fact covered up with Figures of Speech, p. 256. — Implications of Valid Perception, p. 258. — Possi- bility of Error, p. 259. — The Perception of Things and that of Space Relations arise together, p. 260. — Difficulty of determining the Localizing Power of the Senses when taken separately, p. 261. — Complete Perception dependent on Classification, p. 262. — Distinc- tion between the Appearance and the Thing, p. 263. — Origin of the Acquired Perceptions, p. 263. — Source of Sense Illusions, p. 264. Association in Perception, p. 265. — Use made by Berkeley of this Principle, p. 266. — Dependence of Perception on Reproduction, p. 268. Xll CONTENTS. Chapter II. PAGE THE FORMS OF REPRODUCTION . ... 269 No consistent Terminology, p. 271. — Differences of Memory, Fantasy, and Imagination, p. 271. — Memory follows the Order of Mental Development, p. 272. — Laws of Memory, p. 273. — The Possibility of Reproduction depends on the Nature of the Original Experience, p. 274. — Differences in Memory, p. 275. — The Fantasy, p. 276. — Significance of the Imagination for the Rational Life, p. 277. — Con- trol of Reproduction, p. 278. Chapter III. THE THOUGHT PROCESS 280 Two Stages of Thought, p. 280. — Relation of the Judgment to Knowl- edge, p. 281. — Relation of the Universal to the Judgment, p. 281. — Conditions of the Universal, p. 282. — Objections from the Associa- tionalists, p. 282, — Thought and Language, p. 283. — Abstraction, p. 28L — Advantage and Disadvantage of Language, p. 285. — Gene- sis of Judgments, p. 285. — The Judgment in Formal Logic, p. 287. — Artificial Nature of the Logical Doctrine, p. 288. — Truth and Error, p. 290. — Nature of Inference, p. 292. — The Doctrine of Inference in Formal Logic artificial and arbitrary, p. 293. — Concerning Intui- tions, p. 294. — Two Questions to be distinguished, p. 294. — Mathe- matics a Stumbling-block to Empiricism, p. 294. — Belief, p. 296. — Most Beliefs represent, not reasoned Truths, but practical Assump- tions, p. 297. Chapter TV. INTERACTION OF SOUL AND BODY . . . 298 Problem defined, p. 298. — All Interaction mysterious, p. 298. — Seat of the Soul, p. 299. — Meaning of the Question, p. 299. — As com- monly understood the Question both idle and empty, p. 300. — Use of the Body by the Soul, p. 301. — Movements arising apart from Volition, p. 301. — Significance of the Mind for Physical Develop- ment, p. 304. — Two Classes of Physical Habits, p. 305. — The Soul as the Ground of Physical Structure, p. 306. — Cerebral Localization of Mental Functions, p. 307. — Nervous Action in Mental Work, CONTENTS, XlU PAG3 p. 308. — Thought not a Transformation of Nervous Energy, p. 309. — Significance of the Body for the Mental Life, p. 311. — Can the Mental Life go on apart from the Body ? p. 315. — Question admits of no Speculative Solution, p. 316. Chapter V. SLEEP AND ABNORMAL MENTAL PHENOMENA . . 319 Cause of Sleep not fully understood, p. 319. — Depth of Sleep, p. 320. — Fantastic Nature of Dreams, p. 320. — Origin of Dreams in Actual Sensations, p. 321. — Material of Dreams drawn from waking Expe- rience, p. 322. — No single Explanation of Dreams possible, p. 322. — Is the Mind ever Inactive ? p. 323. — The Hypnotic State, p. 325. — Insanity, p. 326. — Its Psychological Features, p. 326. — Grounds of Insanity, p. 327. — Extraordinary Mental Powers, p. 328. PSYCHOLOGY. INTRODUCTION. Psychology deals with mental facts and processes. It aims to describe and classify those facts and processes, to discover and state their laws, and to form some theory concerning their origin and cause. Corresponding to this complex aim, psychology, lilvc all other sciences, may be descriptive and theoretical. We may content ourselves with simply describing and classifying the facts and processes. The result is empirical psychology. From this as a starting- point we may go on to theorize concerning the origin and causes of the facts and processes discovered. The result is theoretical, or philosophical, psychology. But in psychol- ogy, as in most other sciences, these two factors, though logically successive, are practically contemporaneous. No science completes its collection of facts before it begins to theorize ; but the study of fact and the formation of theory go together. This is especially true in psychology, where the statement of the facts themselves often involves a theory. Psychological study may take several directions : — 1. We may study the facts and laws of mind in general, without reference to individual peculiarities or to concrete application. In this case the aim is to discover the essen- tial facts and factors of the mental life. By observation we 1 ^ PSYCHOLOGY. learn the facts and processes ; by analysis we seek to decom- pose them into their ultimate elements ; and, finally, we seek to exhibit the actual mental life as a synthesis of these elements. The product of such study is pure or abstract psychology. 2. The mental life is not perfect from the start, but is subject to a law of growth. We may study it, then, from the genetic side, and trace the order of its unfolding. Such study would have especial significance for the theory of education. Some speculators have thought it possible by this method, not merely to discover the order of temporal development, but also to deduce the later stages as neces- sary results of the earlier ones. We shall find reasons for doubting this view. 3. The mental life is physically conditioned; and, instead of studying mental facts by themselves, we may study them in relation to the organism. This gives rise to a border science, physiological psychology. This does not study physiology -in general, but physiology in its relation to men- tal facts. Nor. does it study psychology in general, but psychology as conditioned by the organism. Pure psychology is plainly the presupposition of all other forms of psychological study ; as pure logic or pure me- chanics is the presupposition of applied logic or applied mechanics. Our work will be mainly in pure psychology, partly descriptive, partly theoretical, and not without some reference to physiology. The facts of the objective sciences are discovered through the senses. The facts of psychology are chiefly revealed only in consciousness. Instead of looking without to find them, we look within. Our method, therefore, must be mainly introspective. Mind can be studied to some extent in history, in institutions, in literature, and especially in lan- guage. In these we see the mind manifesting its nature, and uttering its spontaneous and unsophisticated convic- INTRODUCTION. 3 tions. Language abounds in psychological theories and classifications, which serve as the starting-point even of scientific psychology. Thought, feeling, and volition ; sen- sation, emotion, and understanding; desire, choice, and effort ; body, soul, and spirit, — are illustrations. Such terms represent classifications, distinctions, and theories produced by the spontaneous thinking of mankind. Again, the structure of language itself is an incarnation of the laws of thought ; so much so, that Aristotle sought to determine the essential categories of thinking by an analysis of gram- matical forms. The noun, the adjective, and the active verb are but the reappearance under the forms of language of the thought-forms of substance and attribute, cause and effect. In this sense there can be an objective study of thought. This does not mean, of course, that mind or thought can be presented to the senses ; but only that the nature of mind can be studied in its products. Nevertheless, all our knowledge of mind derived from its objective study must come back to consciousness, either for its meaning or for its verification. No language concern- ing mental facts is intelligible unless we have had expe- rience of the facts for ourselves. No theory of them is verified until we have compared it with the facts in our own Consciousness and have found them to agree. Psy- chology, then, is finally based on introspection. It is a subjective rather than an objective science. This fact has been made the ground for much objection. Some have denied the possibility of inspecting consciousness at all ; others have denied the trustworthiness of conscious- ness. According to the latter, consciousness cannot even tell us whether we are cold or hot. The former claim has the slight psychological foundation that many mental states, pre-eminently emotions, cannot be directly inspected with- out changing their character to some extent ; and therefore they have to be indirectly studied in memory. The latter t PSYCHOLOGY. claim has the slight historical justification that careless Tfriters have often extended consciousness beyond its proper limits ; so that, instead of distinguishing between the facts of consciousness and their interpretation, they have made consciousness cover both. The proper facts of consciousness admit of no scepticism. The one who feels cold is cold ; but it may be that this feeling, instead of its ordinary antecedent, has an abnormal state of the nervous system as its cause. We trust the consciousness even of the insane ; doubt concerns only its interpretation. Ee- membering these limitations, any doubt of the trustworthi- ness of consciousness must seem palpably and flagrantly absurd. Mental facts are nearest of all, and yet psychology develops slowly. The objective sciences are of an earlier birth and a more rapid growth. This is due to several facts : — 1. The mind is objective in its procedure, and thinks of itself last. We tend to lose ourselves in our objects ; and the processes of knowing are so immediate, that it never occurs to us that there is a process. This fact has the highest significance for mental health and development. The mind is taken out of itself and introduced to the great world of things, the knowledge of which is to be its chief occupation and the great source of its growth. The im- plicit trust of the mind in knowledge is shaken only as it stumbles upon contradictions and absurdities, and is forced thereby to analyze its processes and revise its assumptions. 2. The phenomena are complicated, and often admit of no description. Shades of feeling and emotion may be felt, but not described. Language, too, is formed under the influence of external objects, and hence is vague, and often misleading, in its application to mental states. More- over, the mind, because of its objective tendency, becomes INTRODUCTION. O disinclined to look within. Our mental states do not stand out in consciousness with the sharpness of objects in space. Hence the paradox, that there is nothing so hard to study as ourselves. 3. The facts admit of no exact measurement. Physical science depends especially upon measurement, either of size, duration, weight, or intensity. Its facts and laws first become fruitful when they become numerical. The fact of gravitation was known long before Newton, and was of no significance. It was the discovery of its numerical law which first gave it meaning. But thoughts and feelings have no size; and their intensity admits of no exact y^^ numerical determination. 4. Psychology admits of almost no experiment. In phys- iological psychology a little experiment is possible; but in pure psychology no significant experiments can be made. It is, then, neither a mathematical, nor a deductive, nor an experimental science. We can only aim to describe and classify the facts, and to form some conception of their cause. On these accounts many have been pleased to deny that psychology is a science at all. They should rather say that it is not a certain kind of science. A systematic ex- position of a certain set of facts, and a theorizing on them in accordance with their nature, constitute the science of that set of facts. It is only the mentally one-eyed who insist that all facts shall be treated by the same method, regardless of differences of nature. No one has immediate knowledge of any mental life but his own. The mental life of all others is absolutely hidden from our senses. Their thoughts and feelings are open to no direct inspection. All we can see in connection with otliers is sundry changes and movements of the organism ; and all we know of their inner life is reached by analogical inference, whereby we assimilate it to our own. Nor is it easy to find physical marks which certainly denote intelli- o PSYCHOLOGY. gence. In the case of man, they consist chiefly in the voluntary movements and in language. For the animals, Ave have only the voluntary movements. In both cases, the facts of reflex action often make it doubtful whether what we call voluntary movements are really such ; and in both cases, also, their interpretation must be learned from within. It is plain, then, that the starting- point of psychology must be the analysis of the individual consciousness. Oversight of this patent fact has led to the fancy that psychology ought to begin by studying the mental phenomena of the lower animals. The inverted nature of the procedure is apparent; and the result is anthropomorphism in biology. We first assimilate the animal mind to the human mind ; and then we are quite ready to comprehend the latter as the outcome of the former. But, on the other hand, no complete knowledge of the human mind can be gained by a study of the individual consciousness alone. This consciousness itself is evoked only under social conditions ; and the individual is never a complete or perfect specimen of the race. To escape the narrowness and one-sidedness of individualism we need to go out into the open field of the world, — into life, and his- tory, and literature. Only thus can we eliminate individual variations from the type, and get some conception of the human mind in general, as distinct from its imperfect specimens, n In beginning our study several roads open before us. TVe might recite the various schemes of psychological classification, and select some one as a guide for om- fur- ther study. Or we might observe that consciousness is a condition of all mental operations, and begin with a general discussion of the nature and conditions of consciousness. We shall do better, however, to postpone these questions and follow another order. We begin with a discussion of INTRODUCTION. 7 the subject of the mental life ; then we pass to the impres- sions whicli that subject receives from without, and with which the mental life begins ; and, finally, we consider the complex action and reaction upon those impressions in which the developed mental life consists. And first of all, we discuss the subject and the factors of the mental life, leaving their combination for later studj. \ PART I. THE FACTORS OP THE MENTAL LIFE. PART I. THE FACTORS OF THE MENTAL LIFE. CHAPTER L THE SUBJECT OF THE MENTAL LIFE. In all mental experience the self appears as the subject of the mental state ; and the state is referred to the self as its subject. There is no such thing in experience as pure feeling, or knowing, or willing, without a subject that feels, or knows, or wills. Hence we may say that the simplest mental fact is at least double, involving a mental state and a subject of which it is a state. Thoughts and feelings apart from something that thinks and feels are unreal abstractions, like motion apart from something that moves. What is this something ? In spontaneous thought and consciousness the mental subject is given as active and abiding ; and the race has constructed various names for it, as mind, soul, spirit, and their equivalents, to indicate its reality. The whole struc- ture of thought and language also implies it. This con- ception of the mental subject we believe to be correct. It is disputed, however, on two general grounds : — 1. All mental states do not involve a reference to self as their subject. 2. The self, or mental subject, is only a compound pro- duct of mental states, and hence is subsequent to its com- ponents. The first objection properly refers to the philosophy of self-consciousness. It does not deny that the mental acts 12 PSYCHOLOGY. and states are really acts and states of a substantial mind. It only questions whether they always contain a conscious reference to self, or involve self-consciousness. We post- pone its consideration, therefore, to a later chapter. The second claim, so far as it differs from the first, denies the existence of any substantial mind, and regards the mind only as a collective term for the sum of mental facts. As a rule, these mental facts are viewed as sensa- tions, either simple or compounded. Thoughts and feelings exist ; but there is properly nothing that thinks and feels. To this claim the obvious objection is, that we know nothing of mental states, sensational or otherwise, except as affections of some mental subject which has them. Moreover, we never can know of them apart from such connection. Not in the case of others ; for mental facts can never be seen from the outside. Not in our own case ; for then they would be known as ours. There is strictly nothing in experience to suggest that mental states can exist by themselves like things ; on the contrary, expe- rience declares that there must always be something which has them. The opposite view is not based upon experience, but is purely a deduction from a speculative theory. In addition, thought breaks down in the attempt to construe it. Mental states are first broken from the only con- nection in which they have any meaning; and then are mistaken for the ground of their own condition. Again, allowing that they may exist apart from a sub- ject, there is no way of accounting for the unity of the mental life. Let a^ 5, c, cZ, e, etc. be a set of sensations without any common subject, M; there is no way of unit- ing them in a common consciousness. If coexistent, they cannot be known as such ; for no one knows anything of the others, each being only a particular sensation. For the same reason, they cannot be known as sequent. If they were the states of a common subject, iHf, they might THE SUBJECT OF THE MENTAL LIFE. 13 be grasped in a common consciousness and compared as coexistent or sequent, like or unlike ; but otherwise they remain external to one another and without any possibility of progress. A concrete illustration may make this clearer. Let, then, a, 5, 6?, and d be respectively a sensation of color, of odor, of taste, and of sound. Plainly no consciousness can be built out of these elements. The color knows nothing of the odor ; the taste knows nothing of the sound. Each is a particular and isolated unit ; and must remain so until some common subject, iHf, is given, in the unity of whose consciousness these elements may be united. For as long as a^ 5, (?, etc. are all, there is no common consciousness, and hence no rational consciousness at all. We conclude, then, that the mental life, both in its elements and in its combinations, must have a subject. It is not only unintel- ligible, it is impossible, without it. Various devices exist for evading this conclusion. The more uncritical use the language of spontaneous thought without a suspicion of the inconsistency. The less un- critical call their data mental states, states of conscious- ness, etc. ; and, by an easy transformation, states of consciousness become a consciousness of states. Affections of consciousness also are largely spoken of, and conscious- ness itself is proposed as a substitute for the soul. Thus consciousness is hypostasized into something above its alleged elements, and plays essentially the part of an active and rational subject. How there can be states which are states of nothing, and how consciousness, which is itself a mental state, can also have states, are questions passed over in profound silence. It is instructive to note, in the writings of those who reduce the self to states of consciousness, how the abiding element maintains itself under some figure of speech. Thus Hume, in the chapter on personal identity, wliile reducing 14 PSYCHOLOGY. the mind, or self, to a set of dissolving views, also speaks of the mind as the " theatre " in which all this takes place. The reader kindly consents to play the " spectator " ; and thus by means of two figures of speech a philosophical doctrine is firmly established. A more common device is to speak of the mind as a " series " ; and as we posit the series as self-identical in our thought, there is plainly a constant element, — the series itself. Or we are told of " the property of consciousness to know itself as the same in all the changes of its states." Here consciousness itself appears as an abiding subject, which distinguishes itself from its states and knows itself as the same. From such a game of hide and seek, progress unspeakable cannot fail to result. The reasons for this procedure are various. There is often a profound ignorance of the nature of mental facts. More frequently there is a preconceived theory of what mental facts must be ; and of course the facts must be made to fit the theory. This is often the case when psy- chology is approached from the physiological side. The facts are distorted and falsified from the start, in order to adjust them to a predestined explanation. That such a method must lead to error, or nonsense, or both, is self- evident. This inverted procedure has been so common in psy- chology, and has wrought so much mischief withal, that a word or two of commonplace upon method in general may be allowed. First, we are never permitted to make our facts, but only to construe them. Yet in the face of, this simplest rule of method, a large part of psychological study has been directed, not to explaining facts, but to explaining them away. Second, facts must always be taken as they are given, unless some reason be found in the facts themselves for modifying our conception ; and in that case, also, the facts as given must furnish the starting-point. In the THE SUBJECT OF THE MENTAL LIFE. 15 objective sciences this is well understood nowadays ; but in psychology it still needs to be emphasized. The science has been overrun and devastated by theorists, who had already decided what the facts must be ; and by baptizing their arbitrary dogmatism science, they have won not a little glory. They have their reward. To apply these considerations to the matter in hand. It is plain, that, if the mental subject be given as real and abiding, and as an integral element of consciousness, an element without which a rational consciousness is demon- strably impossible, then that subject is to be admitted as a fact until some other facts are discovered which make such admission impossible. The fact may be called metaphysi- cal, or supersensible, or metempirical, or whatever else we may think disagreeable ; nevertheless, we are bound in good faith to recognize it as a fact. The mind as it is must be the foundation of psychology, not the mind as we think it ought to be, nor even the mind as the Zeitgeist has decided it must be. We have, then, a logical right to assume the reality of the mind, and to proceed to study its phenomena upon this assumption, with the proviso, of course, that, if any facts are found which shall conflict with this assumption, we shall modify it accordingly. However, the reality of the mental subject is so stoutly disputed by materialism on the basis of unquestionable facts, that we shall perhaps do better to consider this claim somewhat at length before going further. By materialism is meant the doctrine that the mental subject is nothing substantial, and that mental facts are produced by the physical organism. This view rests upon the fact that the mental life is plainly conditioned by the organism, and that we know nothing of mind apart from a body. The physical and the mental life appear together, advance together, fail together, and disappear together. 16 PSYCHOLOGY. An exclusive acquaintance with such facts, unbalanced by an exact knowledge of mental facts, leads very naturally to the conclusion that the mental life is only a function of the organism. The organism, in turn, is only a special mate- rial aggregate. In ancient materialism the soul was re- garded as real, but material ; in modern times, materialism has come to mean the denial of a substantial soul, and the reference of all mental activities to the physical organism. At first sight this doctrine appears perfectly clear, but in fact it is rather confused. A common way of conceiving it is based upon the conception of organs and their func- tions. The function of the stomach is to digest ; that of the glands is to secrete; and that of the brain is to feel, think, and will. For a long time a favorite formula was that the brain secretes thought, as the liver secretes bile. Of course the brain has other than mental functions; but among its various functions are those of thinking, feeling, and willing. Such attempts to express the doctrine only destroy its tenability. They overlook the fact that the functions and products of all other organs are physical and material. Thus the secretory organs either eliminate their products from the blood, or make them out of matter taken from the blood. If now we are to regard thought as a secretion, it would follow that thoughts either exist in the blood or are made out of blood. In either case they might be collected and looked at, just as we collect and look at bile. But thought itself is immaterial. If we admit that its cause is material, we have still to affirm that thought itself is noth- ing material. Again, it is said, with somewhat less of definiteness, that the brain produces thought ; but the sense of this produc- tion is left unclear. Now all production in the physical realm consists, not in making something else, but in pro- ducing new movements and groupings of matter. The THE SUBJECT OF THE MENTAL LIFE. IT change of motion and the new grouping are the effect. If now the production of thought is to be assimilated to physi- cal production, we should have to say that a certain material grouping is a thought. As n atoms grouped and moving in a certain way do not produce, but are, a chemical molecule, so m atoms grouped and moving in a peculiar way do not produce, but are, a thought. As in the preced- ing case, such thoughts might conceivably be collected and looked at ; and essentially the same absurdity reappears. Once more, thought has been called a movement of mat- ter ; and, as motion is immaterial, this view seems less gross than those preceding. But motion is always the motion of something from one point to another, or along a certain path, with a certain velocity. Hence this view must read : The motion of M from A to B with velocity F is a thought, say a conception in physics or in political economy. But the more clearly we conceive the subject the more im- possible we find it to connect it with the predicate. As well might we call the following line, , an aspiration, or a profound reflection, or a flash of insight. These attempts to illustrate the doctrine only serve to make more clear the difference between physical and men- tal facts. All that is left is the claim that in some obscure way the mental life is the outcome of the physical organ- ism. This doctrine we propose to examine. Throughout the argument matter will be conceived as atomically dis- crete, as that is the only conception admitted in physical science. Materialism rejects the reality of the mental subject as apparently given in consciousness and as assumed by spon- taneous thought, because the mental life is found to be pro- foundly dependent upon the organism, and more especially upon the brain and nervous system. But such dependence is ambiguous, and may be explained by either of two hypotheses : — 2 18 PSYCHOLOGY. 1. We may suppose that the organism produces the men- tal facts. This would explain the observed dependence. 2. We may suppose that the mind is distinct from the organism, but is conditioned in its activities by the organ- ism. This also would explain the observed dependence. The decision bet\teen these views can be reached only by studying all the facts of the mental life. If we find that one better explains and expresses the facts than the other, the decision must be in favor of that one. But before pro- ceeding, it may be well to emphasize the ambiguity of the facts in question. For the most decided spiritualist, the body is the means for educing and inciting the mental life, and for putting tlie mind in connection with the outer world. Hence the mental state must be affected by the physical. If the nerves be disordered, they can only lead to disturbed mental action. An immature organism would not furnish the mind with the stimulus for a mature mental life. Again, as we know of other minds only through the organism, it follows that the disappearance of the latter would end all manifestation of the former. It is the illogical imagination which finds in the facts of mental dependence upon the organism a sure proof of materialism. Common facts illustrative of the dependence of the mind upon the body, such as the influence of stimu- lants, the need of sleep, the depressing effect of familiar diseases, etc., do not affect us. But uncommon facts, as some occult discovery in brain physiology, or the influence of some new drug, these have profound significance. Yet, logically, the influence of a cup of coffee has as much sig- nificance as the newest fact of the hospital or laboratory. All alike are but specifications of the fact, known and con- fessed by all, that the mind is conditioned by the nature and state of the body. If these facts were all, the result would be a drawn battle. But there are certain capital facts of the mental life which make materialism an untenable theory. THE SUBJECT OF THE MENTAL LIFE. 19 The first great difficulty which materialism meets is the complete uiilikeness of physical and mental facts. Body has form, position, solidity. Thoughts and feelings have none of these. The attributes of one cannot be ascribed to the other without absurdity. If we pass below visible body to the component elements, we come no nearer to thought, so long as we retain only the conceptions of mat- ter which appear in physical science. The phenomena of matter as conceived by the physicist consist entirely in aggregation and movement ; and the forces of matter are without exception moving forces, that is, their effect con- sists entirely in modifying the movement, position, and aggregation of the elements. But it is a simple matter of definition, that the elements, as thus conceived, will never explain thought, unless we assume that a given grouping is thought, which is absurd. All that our system provides for us is aggregation and movement ; and no reflection on changes of motion and grouping will ever bring us to a point w^here we shall see that the next step must be a thought or feeling, something wholly incommensurable with either or both. We can conceive that such a system of elements might be so connected with a mental subject that their changes should be the ground for a thought or feeling arising in that subject ; but otherwise we begin and end with the elements variously grouped and moving. A false conception of physical causation often misleads us here. We fancy that the elements may cause something apart from themselves, but in sound science all physical effects consist in some change of physical states re- sulting in some change of position, aggregation, and movement. An apparent exception to this view is found in the facts of sound, light, etc. In these cases the elements produce effects unlike themselves. The sound is unlike the instru- ment ; the light is unlike the vibrating ether. 20 PSYCHOLOGY. The exception is only apparent. The vibrating instru- ment produces a vibrating atmosphere, which produces a vibrating nerve. So long as we remain in the physical realm, Ave have only movement, nor can any one pretend that in this realm a vibration must at last be reached which will have for its consequent, not a vibration, but a sound. The same applies to light. The exception is based on an ambiguity of the terms. The instrument does not produce sound in the psychological sense, but only vibration. The vibrating ether does not produce light in the visual sense, but propagates vibrations. And as long as we remain in the physical realm, with only physical conceptions, nothing more is possible. A second objection to this claim has been based on the transformation of energy. This doctrine was supposed to teach that all material forces may pass into one another, or rather that there is but one force which manifests itself under various forms. From this it was concluded that physical energy may become mental energy, and conversely. This was pure mistake. The forces of matter are neither correlated nor transformed. Each of these remains as dis- tinct and separate as ever. The doctrine applies only to the energies of matter, and these are nothing independent of the elements, but only their power of doing work, that is, their power to produce changes in material movements and aggregates. In whatever form they appear, they have this common quality, that they are expressed in some form of movement or aggregation. So long as we employ only those conceptions of matter and force which suffice for physical science, it is strictly impossible to bring thought within the chain of physical cause and effect. It rather remains outside of it and in- commensurable with it. So much may be received as uni»- versally allowed. Matter as the movable explains only motion and aggregation. But may it not be that we have THE SUBJECT OF THE MENTAL LIFE. 21 thought too meanly of matter ? If we allow that the phys- ical properties of the elements will not explain the mental life, why need we go outside of the elements for a special ground ? Why not rather posit in the elements, along with the physical properties, another set of mental properties, different indeed from the others, yet belonging to the same subject ? In certain relations matter manifests gravity ; in certain others, affinity; in still others, magnetism; and finally, in others it manifests vital and mental properties. Traces of this view are found throughout speculation. It first appears in the hylozoism of the Greeks, and may be called hylozoistic materialism. Modern materialists generally resort to it, and call for " new definitions of matter." There are many differences of detail among those who hold it, but all agree in assuming some mystic principle in matter which is the ground of its vital and mental manifestations. Some regard mentality as co- existent with all materiality, and propose to endow every atom with a kind of soul life, and to found even attraction on a kind of sentiency. Others allow the mystic attribute to play a part only in connection with the organism ; else- where it has no significance. Some, as Hobbes, would endow the elements with " actual sense and perception," though lacking " the organs and memory of animals to express their sensations." Others would attribute to them only a confused sentiency, which in some peculiar way develops under favorable conditions into our conscious mental life. In fact, the theory has never been thought out into definiteness, but has existed as a vague conception of an indefinite possibility, upon which materialism might draw whenever it got into speculative straits. There is only the general conception that matter is more and better than we have been used to thinking. It is a double-faced substance, has an inner side, a subjective aspect, and is essentially something mystic and transcendental. 22 PSYCHOLOGY. At first sight this view seems promising. It appears to overcome the opposition between materiality and mentality, at least to some extent. Instead of leaving them glaring at each other across an impassable gulf, it unites them as opposite manifestations of the same thing. But, first of all, let us try to understand the doctrine. It is clear, to begin with, that this view is a distinct abandonment of the vulgar forms of materialism. There is no possibility of deducing mental facts from any physical facts and processes whatever. Matter, as we know it in physical science, is forever inadequate to the explanation of the lowest forms of sensation ; but matter, as we do not know it, accounts for the mental life. Its physical proper- ties explain only physics ; its mystical properties explain life and mind. Moreover, it is as impossible to bring phys- ical and mental facts into linear order on this view as it is on the spiritual theory. Each set of facts remains external to the other in both cases ; but in the former we seem to secure a certain unity in our theory of things by attributing these incommensurable properties to the same subjects, instead of to two incommensurable classes of subjects, mind and matter. In order to make the doctrine perfectly clear in its mean- ing, one or two other points have to be cleared up : 1. What are its relations to established physical science? 2. What is the relation of the physical and the mental facts in this theory ? As to the first point, physical science is built upon the denial of the hylozoistic conception of matter. Hylozoism for ages prevented the birth of physics, and a return to hylozoism would be its death. Physical science is built upon the sharp mechanical notions of inertia, momentum, velocity, mass, energy, etc. By the mental travail of centuries it has wrought these notions out ; and all its successes have been due to them. Physics, there- THE SUBJECT OF THE MENTAL LIFE. 23 fore, had rather let other reahns alone, than by annexing them to destroy the clearness and sharpness of its own conceptions. Where these conceptions apply, hylozoism is excluded. This point deserves attention, as materialism has Won considerable prestige from the mistaken fancy that it builds upon physics as its chief corner stone. In fact, however, the more faithful we are to physical conceptions, and the more clearly we grasp them in thought, the plainer becomes the impossibility of reaching the mental life. Physics needs no new definitions of matter. Materialism insists upon a new definition of matter. The second point concerns the relation of physical and mental facts. We may call the changes of position, group- ing and movement, the physical series, and the clianges of thought, feeling, etc., the mental series. How does this doctrine conceive their relation ? This point has seldom been thought out. Several con- ceptions are possible. 1. The two series may be conceived as mutually inde- pendent, the pliysical series going along by itself, and the mental series by itself. But in that case we should simply have elements acting in two incommensurable ways, neither of which would have any significance for the other. In that case the mental series would be self-contained and independent so far as the pliysical series is concerned. Nothing that happens in the latter would be any ground for the movements of the former. The outcome would be idealism. 2. A rhetorical misunderstanding of the doctrine of cor- relation and conservation of energy has led to another view, in which both the physical and the mental series are mutually convertible expressions of a common energy. Why the one energy should have these antithetic forms ; in what way one conditions the other ; whetlier one form 24 PSYCHOLOGY. might pass entirely into tlie other, so that all the energy of the system' might become mental energy ; whether phys- ical energy disappears entirely from the physical system and vanishes into the mental realm ; and whether there are irruptions of mental energy into the physical system, so as to produce a series of faults in both systems; — these are questions to which there is no answer. But a rhetorical misunderstanding calls for no elaborate criticism. 3. The desire to maintain the continuity and indepen- dence of the physical series has led to another conception, as follows. Each physical antecedent is expended in pro- ducing its physical consequent, and each consequent is fully explained by its antecedent. The physical series goes along by itself, receiving no modifications from with- out, and expending no energy except to produce new move- ments and groupings of matter, which effects in turn become causes, and produce other movements and group- ings. The mental series is not caused by this series in a physical sense, but only attends it as a shadow attends its substance. Like a shadow, it costs nothing and determines nothing. Life and history are pure automatism. Thought attends nervous action, but does not affect it. Why it should do so, we cannot tell. Why it should attend one form of nervous action rather than another, is equally un- known. We must either refer it to magic, or else affirm some obscure harmony between specific forms of nervous action and the thoughts which are said to attend as their inner " face " or otherwise. In fact, those who have held this view have never been careful to think out its applications. Sometimes, in sheer forgetfulness, the mental series is called an aspect or phenomenon of the physical series. We have seen that the mental series is never phenomenal to any one but its subject ; and where there is no subject there are no " aspects " and no " phenomena." Suppose n atoms turn in a left-hand spiral, love is an aspect of this fact. But for THE SUBJECT OF THE MENTAL LIFE. 25 whom ? For the atoms ? If so, for all or for each ? If not for the atoms, for what or whom ? For the motion itself, perhaps ! 4. In order to leave no unintelligibility untried, some have claimed that the two series are identical. The thing- series considered subjectively is the thought-series ; and the thought-series considered objectively is the thing-series. So far as this is intelligible, it is absurd. The thing-series is a set of moving molecules ; the thought-series is a group of mental states. That one should cause the other, is an intelligible proposition ; that one is the other, is nieaning- less. Moreover, this theory implies mind as the condition of its own existence ; for the two ways of looking at the same fact seem to be founded, not in the reality, but in the mind which grasps it. How there can be two points of view is an important question for this theory, but as yet it has not been answered. So far we have only sought to understand hylozoistic materialism. We have now to show that no interaction of a plurality of elements, no matter how mysterious or two- sided they may be, can explain the mental life without assuming a unitary subject of that life. The chief difficul- ties are these : — 1. Thoughts and feelings demand a subject, and have no meaning apart from it. Materialism, in alliance with sen- sationalism, has generally falsified experience at the start, by assuming that they may exist without a subject, and it derives most of its probability therefrom. If it were clearly seen that thoughts and feelings imply something that thinks and feels, materialism would seldom begin. If the mate- rialist saw that he must explain, not only the occurrence of mental states, but also the existence of a mental subject, his task would seem more formidable. But we have seen that the mental subject is a precondition of the mental state. What, then, thinks and feels in my thinking and 26 PSYCHOLOGY. feeling ? We cannot say that the brain does ; for (1.) while the brain may produce the thought, there is no ground for saying that it thinks the thought ; and (2.) in any case the brain is an aggregate, and as such has its reality only in the elements which compose it. Apart from these it is nothing. Hence, to say that the brain thinks and feels, can only mean that the component elements think and feel. But which ? All, or some, or only one ? If only one, the unity and reality of the mental subject is admitted. If all or many think, what is the relation of their thoughts to mine ? If they all think my complete thought, my thought is not explained unless I identify myself with some one of the elements ; and then all the reduplications of myself in the other elements are superfluous. We may say that my thoughts are not in the elements at all, but result from their interaction as a function, or resultant, of the whole ; but this view is untenable for the following reasons. Suppose n elements, a, 5, c, cZ, etc., endowed with sundry mystic possibilities, and entering into a highly complex in- teraction. As a consequence thereof, they may all enter into the same inner state, W2, or into a series of states, w, w, 0, r, etc., different for each. These inner states, owing to the mysterious double-facedness of the elements, may be considered as of a mental nature. The only pos- sible outcome of the elements' interaction is a modification of their space-relations and the production of these inner states. But each of these states is inseparable from its own subject. There is no way whereby m, n, o, r, etc. may leave their respective subjects, and congregate in the void to form a compound mental state which I call mine. Such a notion would be like that of a series of motions which should break loose from their subjects and compound them- selves in the void to form a new motion which should be the motion of nothing. Hence the mental states of the elements must be subjective to the elements themselves, in THE SUBJECT OF THE MENTAL LIFE. 27 which case my mental states are not explained unless I am identified with some one of the elements. But I cannot be identified with any element without thereby removing it from the physical series ; for that element is known only as having mental qualities, and is not known as having any physical qualities whatever. Whereas, too, all the others are in a state of constant change, that element is given as fixed and abiding. But if my mental states are not sub- jective to any one or all of the elements, then outside of a, 6, e, c?, etc. there must be another element, J/, in such interaction with a, 5, c, c?, etc. that they furnish it with the condition of developing mental states within itself. That M is myself. 2. A rational life by its very nature demands a unitary consciousness and a unitary subject. For even admitting that a series of states of consciousness is possible without a subject, we have made no progress toward a rational life. In that case, a, b, e, d, etc. are discrete units of feeling, and can never constitute a single consciousness. We repeat the argument already given. Suppose a is a sensation of color, b one of sound, c is a pain, d is an odor, etc. Each is an isolated existence, and is unable to advance beyond itself. A consciousness com- posed of such elements would be no consciousness at all. These states of consciousness must in some way be turned into a consciousness of states. But this latter conscious- ness cannot be attributed to any member of the series without violating the primary agreement, which was that each member is only a particular mental state. If a, in addition to being a state of consciousness, is conscious of b, c, d, etc., and is able to discern their nature and rela- tions, it has all the functions of mind attributed to it. Yet, plainly, if there is to be a consciousness of coexistence or of sequence, of likeness or unlikeness, of unity and plural- ity, there must be a consciousness which, instead of being 28 PSYCHOLOGY. a state of consciousness, is a consciousness of states. But this is not provided for bj the coexistence and sequence of the states, but only by some unitary subject, which, standing over against the states, grasps them all in the unity of a single apprehension. Before a, 5, c, d, etc. can become elements of a rational life, M must be given. 3. Again, thought by its very nature must have a single subject. To think is to compare, to distinguish, to unite. But in order to any of these operations, one and the same conscious subject must grasp in the unity of a single act the things compared, distinguished, united. If ilf conceives <2, and iV^conceives 6, no relation can be established between a and h. The same i!f must grasp both a and h in one con- sciousness before thought can begin. All reasoning has the implication. Unless the same subject grasp both prem- ises in a single conscious act, there can be no conclusion. The same is true of the consciousness of plurality. The knowledge of the many is possible only through the unity of the one. Hence not merely the consciousness of self as one reveals the unity of self, but much more does con- sciousness of the many compel the same assumption. 4. The same conclusion is compelled by the facts of memory. What remembers ? The spiritualist says. The soul remembers ; it abides across the years and the flow of the body, and gathering up its past carries it with it. The materialist must explain the fact. We cannot say that the brain remembers, for the same reason that we cannot say that the brain thinks. The elements remember, then, but how ? Those which had the experience are gone, and yet the new-comers know all about it. The original elements, 6x, 6, c, d, contributed nothing to Z, m, n^ r, the present elements ; and yet Z, w, 9^, r, know what happened to a, h, c, d. The materialist can only say that memory depends on the form of nervous action, rather than on the identity of the component elements. But in that case we THE SUBJECT OF THE MENTAL LIFE. 29 are left without any subject for the memory, and memory loses all relations to time. An organism made at first hand from the inorganic would have just the same mental life as another of the same structure which might have lived in the past. The former would have the same memories, beliefs, doubts, and expectations as the latter, and would be equally at home in every relation. But in that case memory would only be a present outcome of a special form of nervous action, and would lose all reference to time. And with all this heroic treatment, the facts would still be unmet. Reasoning similar to that already employed would show that memory demands a unitary mental subject. Memory involves a consciousness of temporal relations between certain elements of experience ; and this con- sciousness falls asunder without the unity and identity of the subject. Materialism in its hylozoistic form succeeds no better than in its vulgar form in explaining the facts of the men- tal life. There are certain great capital mental facts which cannot be explained as the outcome of any aggregate of physical elements, no matter how mysterious, as long as a special mental subject is denied. Hylozoism merely con- fuses two realms, and loses the advantages of both. On the one hand, it offers a conception of matter from which physi- cal science has steadily grown away, and which absolutely nothing in experience justifies. On the other hand, it can make no use of the assumed mystic properties in explaining our mental life. They would be mischievous in physics if allowed to influence our conceptions ; and they are abso- lutely worthless in psychology. They must be ruled out, therefore, from both sciences. Materialism fails to explain the simplest facts of con- sciousness. On the other hand, spiritualism fits into the facts so well that to spontaneous thought it seems to be a direct utterance of consciousness itself. In addition to the 30 PSYCHOLOGY. previous considerations, certain implications of materialism are to be considered ; first, in its bearing on action, and second, in its bearing on our trust in knowledge. If these prove absurd or inadmissible, then the theory is doubly untenable. First, as to the bearing of materialism on action. For materialism the organism is all, and all physical movements are physically determined. These movements are accom- panied by thoughts and feelings, but the latter are never causal. They are the mental equivalent, or representative, of the physical process, but all reality and ground of move- ment are in the physical series. A volition, for example, does not determine action, but is rather only the symbol in consciousness of the physical process which underlies both the symbol and the appropriate action. The symbol counts for nothing in the dynamic sequence of events, but stands apart from the chain of cause and effect as a shadowy attendant, costing and causing nothing. It is plain that this is the extreme of automatism. The common thought is, that in the movements of history, the foundation of states, the founding of families, the activities of invention, commerce, literature, etc., the human mind has manifested itself as controlling. But on the theory in question, all this vast activity has taken place without any intervention of thought whatever. Thought may have at- tended the process, though even that becomes doubtful, as the only reason for affirming thought in another person is the conviction that his activities need thought for their ex- planation ; but in any case thought has added nothing. The elements which produced the process knew nothing of it, nor of the thoughts they are supposed to have produced. The presencer of the thoughts, instead of being a help, was rather a hindrance, as they represent so much extra work. To take a single illustration, the Principia of Newton, and La MScanique CSleste of Laplace, w^ere not the out- THE SUBJECT OF THE MENTAL LIFE. 31 come of any thought whatever, but of a series of physical processes in two organisms, called, for distinction's sake, Newton and Laplace. There was a highly complex series of nervous and muscular processes in happy and profound adjustment to the environment, and the outcome was that propositions and scholia and corollaries were written down in the most astonishing profusion, the whole being illus- trated by diagrams, and founded on, or explained in, the most extraordinary series of equations. These are all bound together so as to form a chain of reasoning of the most cogent kind, and to express a series of the profoundest conceptions of physical astronomy. Yet the nerves which did all this knew nothing of the solar system, or of mathe- matics, or of themselves, or of what they were doing, or of the problem at which they were working, or of the attend- ant thoughts which they were producing. These thoughts, indeed, which on the common theory are the ground of the entire process, and its only possible explanation, are on the present theory only so much extra work, and hence are an embarrassment rather than a help or guide. This might be called an extreme proposition. The bearings of materialism on knowledge are next to be considered. The following points are to be noted. 1. Suppose matter can think, it does not follow that it must think rightly. Its thoughts might well be of the nature of fancies or dreams, which, while mental states, nevertheless represent no facts of reality. But, remem- bering that the physical series is known only through the thought-series, it is plain that materialism must not only provide for a thought-series in general, but for one parallel to the nature of reality. Otherwise knowledge has no validity, and the foundations of materialism vanish. 2. At first sight this seems easy. Since thought is the inner face of the physical process, we may suppose that the inside must correspond to the outside, like the con- 32 PSYCHOLOGY. cavity and convexity of a curve. But, to get any help from this view, we must suppose that the thing known is that part of the physical process which lies over against the thought, or which produces it. But this is never the case, for then our thought would be a repetition of the nerve processes, whereas it never reports these directly, but reports rather facts and processes existing or going on outside of the organism entirely, such as the facts of physical nature, the thoughts and feelings of others, etc. Oddly enough, thought never grasps except indirectly the organic processes on which it is assumed to depend, or of which it is said to be the inner face. Whence, then, the parallelism of the thoughts arising within the organism with the system of nature, which is independent of the organism ? Either we must abandon knowledge to scepti- cism, or we must assume that matter by its nature is shut up to right thinking. Thus we come to affirm an opaque harmony between matter and thought. Some have sought to escape this admission by appealing to natural selection. According to them wrong thinking must lead to collision with reality, and thus to destruction. Right thinking, again, will lead to survival, and by he- redity will be transmitted. Plence, in the course of time, natural selection will kill off all false thinking, and will adjust the human mind to reality, yet without assuming any original harmony between thought and thing. 3. This appeal is inconsistent on the part of the mate- rialist for several reasons. a. It contradicts the asserted powerlessness of thought. If thought . attends, without affecting, the organism, its adjustment or misadjustment is equally insignificant for survival. Organisms survive because of their physical ad- justments to the system, and not because of mental adjust- ment. They perish also because of physical misadjustment, not because of mental misadjustment. Hence natural THE SUBJECT OF THE MENTAL LIFE. 33 selection can never come into play to secure mental adjust- ment. It can only secure physical adjustment, but there is nothing in the idea of such adjustment which implies that thoughts must be parallel to facts. h. Allowing that natural selection can act, the principle is too narrow in its range to make it of any use as a crite- rion of thought in general. Plainly it could do nothing except in case of truth related to physical survival, whereas most truth has no such relation. The bulk of theory and speculation has such scanty reference to survival, that some other foundation must be sought ; and for the mate- rialist there is none but the assumed harmony between thought and fact in the nature of matter. c?. Again, if the theory be allowed as a determining prin- ciple of belief, materialism is ruled out forthwith. For in that case wide-spread and enduring beliefs are the only ones which have any credibility. Beliefs contemporane- ous with man, or at least with civilization, catholic beliefs which have developed and established themselves through the ages, have absolute right of way, compared with local, sectarian, upstart beliefs. The former represent the sift- ing action of many centuries, and have the fullest bene- diction of natural selection. But natural selection has not dealt hitherto in materialistic beliefs. The proportion of materialists to spiritualists is probably less than that of idiots to persons of sound mind. Hence, as materialists, we must be careful how we appeal to natural selection, for thus far it has gone dead against us. d. If it be said that the principle has not yet had time to work, it can be shown that its future direction will be the same as in the past. There can be no doubt that materialism is a depressing belief compared with spiritual- ism. The welfare both of the individual and of society demands sacrifice, self-control, and high endeavor ; but these are born only of high conception and lofty hopes. 3 34 PSYCHOLOGY. Materialism furnishes depressing views of man, — of his nature, possibilities, and destiny ; and hence, in the long run, under the influence of natural selection, it would have to yield to the more hopeful and inspiring view. Plainly natural selection is a dangerous ally for the materialists. We are, then, shut up to affirm that matter by its nature is determined to right thoughts. But here the fact appears that most beliefs produced by matter are by hypothesis false. Since matter is the sole source of knowledge and of mental states, it is to blame for all superstitions, theology, philosophy, etc., as well as for the truths of materialism. Matter has founded the spiritual school of philosophy, as well as the materialistic school ; indeed, thus far it has favored almost exclusively anti-materialistic beliefs. Now, since for one sound belief matter has produced a myriad un- sound and grotesque ones, when shall we believe it ? These false beliefs cannot be attributed to bad training, the con- tagion of example, the influence of superstition, because none of these things seem able to influence matter, and, if they exist, matter itself is responsible for them. The most natural conclusion under these circumstances would be, that all belief is untrustworthy. That which has such an irresistible tendency towards error, superstition, and falsehood as matter has, must surely be untrustworthy in all its deliverances. But allowing that some truth ex- ists, we must have a standard whereby we may disengage it from this tangle of error. We shall find it hard to dis- cover a standard which will enable us to save knowledge and materialism at the same time. 1. The test of truth in this system is not necessity; for truth and error alike are brought forth with equal necessity by the nervous processes. 2. It is not reason ; for reason is no self-centred, self- verifying faculty, but only a shifting of mental states as determined by the mechanics of the nervous system. THE SUBJECT OF THE MENTAL LIFE. 35 3. It is not the majority ; for the majority is anti- materialistic. 4. We get no help from assuming it to be found in the normal brain ; for then we need a test for the normal brain. It clearly is not the majority brain ; for this is anti-material- istic. Inquiry would show that the normal brain is the ma- terialist's brain, and is known to be normal by hypothesis. 5. The standard of truth is not success or practical util- ity. Materialism is a depressing and paralyzing doctrine. 6. In fact, materialism has no standard of truth. Indeed, the distinction of truth and error cannot exist for it. Since physical processes are all, we might as well talk of true or false bile, or true or false blood, as to speak of true or false ideas. Ideas are the inside of nervous pro- cesses, and their coming and going are. not determined by their logical truth or falsehood, but by the dynamic rela- tions of the corresponding nervous states. But the ideas of physical strength and weakness are incommensurable with the logical ideas of truth and error. If materialism be true, reason is exploded. Instead of being the highest science and philosophy, it is rather the death of both. We conclude, then, that materialism is untenable, for two leading reasons. It fails to explain even the simplest mental fact ; and its implications are suicidal. To sup- port itself it is forced to affirm qualities in the elements of which physics knows nothing, and when it has con- structed its " new definition of matter," it stands absolutely helpless before the simplest fact of our rational life. It is further compelled to turn men into automata, and to af- firm that all human affairs and activities are carried on by agents which know nothing of themselves, or of one another, or of the laws according to which they work, or of the effects they produce. Having thus denied all the truths by which men and nations live, materialism is finally compelled to deny truth, and to drag reason itself down into 36 PSYCHOLOGY. utter scepticism. Refusing to surrender, it ends the siege by blowing up the citadel, leaving only mental chaos behind it. We began the discussion of materialism by pointing out that the facts upon which it rests are ambiguous. We may suppose that the organism produces the mental facts, or that it simply conditions the activities of something other than itself. A further study of mental facts, however, convinces us that the former supposition is untenable, and shuts us up to the latter. Hence we view man as we find him, as a dual being, body and soul. By the mind we mean the soul in its intellectual activities. The true man is the soul, but the soul is connected with an organism which conditions the mental life. The body, however, though other than the soul, has still the profoundest significance for the soul in all its activities. It is an instrument for eliciting and guiding the mental development, and for put- ting the soul into relation with the world of things. This conclusion, moreover, does not rest upon our ignorance of brain physiology, so that advancing knowledge may at any time displace it. It rests rather upon the essential nature of consciousness, and the insight that the unity of con- sciousness can never result from the interaction of any plurality of things. Whatever progress brain-physiology may make, it will never bring us one step nearer to mate- rialism ; and all the discoveries in this realm will have to be interpreted in accordance with this fact. This view of course does not explain all difficulties, nor answer all questions ; for example, it does not explain how body and soul interact, nor the form of their interaction. It does not explain the nature nor the extent of the soul's dependence on the body. It does not tell what physical facts are connected with given mental facts, nor even why there should be any connection. It does not explain the mental effects of opium, or alcohol, or disturbances of the THE SUBJECT OF THE MENTAL LIFE. 37 brain. It does not explain the physical effect of joy, or fear, or depression. So far as these problems can be solved, it must be by experience. Some of them admit of no solution. Experience may reveal that certain facts in the physical series are accompanied by certain facts in the mental series, and conversely ; but the ground of their connection will always remain a mystery. Physiology, psy- chology, and pathology, working together, have the task of finding the actual relations of the two series ; but before this can be done, the two series must be separately studied by the methods proper to each. No peering even into the liv- ing brain would give the least suspicion of the mental series attending it. Conversely, no inspection of consciousness can reveal the physical facts by which it is conditioned. In this way, by keeping separate things separate, we may hope to learn something of the psychical significance of the body, and of the physical significance of the mind. But if the two series were fully known, and were even found to run parallel throughout their entire length, we should still have simply a coincidence to be accepted, not a connection to be understood. But while this view docs not remove all difficulties, it does relieve some. It enables us to use the language of spontaneous thought without constant inconsistency. It frees us from the need of talking of feelings which be- long to no one, and of mental states which are states of nothing. It also removes the necessity of hypostasizing consciousness into a fictitious mental subject in order to escape admitting a real one. It makes it unnecessary to repudiate all the utterances of our spontaneous conscious- ness. Finally, it saves us from the somewhat tedious superficialities and drolleries of materialism, — a service by no means to be undervalued. Such are its negative advantages. Positively, it provides for the unity and con- tinuity of the mental life ; and it agrees so well with our 38 PSYCHOLOGY. spontaneous consciousness, that it almost seems like an immediate deliverance of the same. Finally, by displacing the manikin conception of humanity, it provides for some consistent recognition of the ideals and practical principles by which both men and nations live. The dreary folly of laboriously building up speculative theories, which every hour we practically deny, may seem very brilliant for a while, but it grows tiresome at last. SENSATION. 39 CHAPTER 11. SENSATION. By sensation we mean that peculiar affection of tlie sensibility which is referred to some extra-mental cause. In this respect, sensation differs from emotion ; for the latter, while a state of the sensibility, arises from the nature of our mental states themselves, and is not referred directly to any external cause. There is no need to inquire whether this objective reference be objectively valid ; for in any case it is actually made, and serves as a mark of distinction. In our mature life, sensations have a double reference. (1.) They are referred to the self as their subject, and (2.) they are referred to extra-mental objects, either as their qualities or as caused by them. In the latter refer- ence, sensation passes into perception. Thus the sensa- tion of light seems not so much a subjective state as the perception of an objective quality. Our present study deals with sensations only as subjective states. Of the conditions of sensation nothing can be said apriori. A certain nervous cliange is attended with a sensation of light, another with that of sound, another with pain, etc. But why they should be attended witli certain sensations and not with others, no one knows. Or why they should be attended with sensation at all, while others are not, is equally unknown. Or why sensa- tion should result only from movements in the organism, and not from extra-organic movements, is likewise myste- rious. The doctrine of the clairvoyants, who claim to see by some direct gaze of the soul, and without mediation of 40 PSYCHOLOGY. the organs of sense, is in itself no more mysterious than the actual order of experience, Apriori, one order is as possible as another. The actual order must be learned from experience. The actual conditions of sensation are found in some form of nervous change. The causes of this change are often external to the organism ; often they are within the organism, and sometimes they are in the mind itself. Cor- responding thereto, we have respectively the extra-organic or objective sensations, the organic, and the subjective sensations. Supposing the end of a nerve disturbed in any way, this disturbance must be propagated to the brain. What hap- pens in the nerve is purely a matter of speculation. A thoughtless form of speech often regards the nerves as carrying the sensation to the mind, but a moment's reflec- tion reveals the absurdity. Sensations are not things which can be handed along from one atom to another, as a letter is passed from hand to hand, and hence, if the nerves were full of sensations, they would not explain mine. In accordance with our general views of matter, we regard the nerves as a molecular complex ; and hence we must hold that molecular movement is the essential phenomenon of nervous action. At all events, it is found that some- thing takes place in the nerve, and that this is propagated through the nerve at a rate of from one hundred to three hundred feet a second. It is further found, that no sensa- tion results if the nerve-line be not continued unbroken to the central organ. When this is the case, and the nervous affection is propagated to the brain, there results a fact of a new order, a conscious sensation. This is purely a mental state. It is not contributed to the mind by the nerves ; and the nerves themselves do not feel. Sensation is a mental reaction against nervous action. This fact is inexplicable on any theory. No materialist SENSATION. 41 would claim that any analysis of ether- or air-waves, or of a vibrating nerve, would ever lead us to the point where we should see a sensation emerging as its necessary con- sequence. He would be compelled to accept the fact as a mystery. On the other hand, no spiritualist would claim to know why a given form of nervous action should be attended by one form, and intensity, of sensation, rather than another. There is nothing in the cause to suggest the effect ; and, conversely, nothing in the effect to suggest the cause. Just as no reflection on a vibrating nerve gives sensation as its effect, so no reflection on the sensation reveals a vibrating nerve as its cause. All but the circle- squaring type of minds have abandoned the attempt to tell how, or why, nervous action is followed by sensation ; or why one form of nervous action is followed by one form of sensation, and another form by another. All study in this direction is lost, and indicates utter inability to deal with the problem in general. The two orders are con- nected in fact ; but there is nothing difficult in the notion that the mental series should be connected with a totally different pliysical series, either in other animals or in other spheres of being. Thus far we have considered the conditions of sensation only in the most general way. In their further study we begin with the nervous excitant or stimulus. This is different for different nerves. Speaking broadly, we may say that the normal excitant for the optic nerve is light ; for the ear, sound ; for the touch, contact and a cer- tain measure of resistance ; for the sense of temperature, heat ; and for the senses of taste and sn^ell, certain chem- ical changes in the corresponding nerves. In most of these cases, however, the action of the excitant is more complex than was formerly thought. The structure of the eye is such as to allow only ether-vibration to reach the optic nerve, but the simple falling of light upon the nerve does 4^ PSYCHOLOGY. not produce the sensation of light. Both the optic nerves and fibres are insensible to light, as appears from the so-called blind spot and the Purkinje figures. Behind the optic fibres is the region of the rods and cones, and the vis- ual purple ; and here it is that the sensibility to light is found. It has been suggested that photo-chemical changes in this region are the true stimuli. In the case of the ear, sound is the external stimulus ; but the auditory mechanism is extremely complex, and the functions of its several parts are unknown. How auditory impulses are generated in the organ of Corti is as mysterious, as how visual impulses are generated in the region of the rods and cones of the eye. ^ Sensations of temperature are due to changes of heat ; but the heat, instead of acting directly upon the nerve, may produce its effect by various modifications of the surrounding physical structure. The skin and tongue, likewise, have curious structures, whose function may be to give the external excitant a form adapted to the nerve. It has been supposed that sensa- tions of touch are due to one set of terminal organs in the skin, and sensations of temperature to another ; but how the different stimuli act upon these organs is unknown. Smell, too, is due to contact of odorous particles with the olfactory membrane, but it seems necessary that the sub- stance be in a gaseous form. When the nostril is filled with rose-water, no odor is perceived ; though this might well be due to a temporary paralysis of the nerve, as filling the nose with water suffices to suspend smell for a time. There remains, therefore, a great deal that is mysterious in the action of the external stimulus upon the nerves. In the case of the organic sensations, nothing is known of the form and mode of action of the stimulus. A certain state of the muscles, or viscera, or the nerves themselves, becomes a ground of sensation, but why, or how, is unknown. SENSATION. 43 For objective sensations the excitant is generally peculiar for each class ; for light, ether-waves ; for sound, air-waves ; for taste, chemical action, etc. But it appears that any agent which affects the special nerves may produce the appropriate sensations. Thus a blow on the head, or pressure of the eyeball, may produce the sensation of light ; a blow also may produce a ringing in the ears ; while electricity serves to excite all the senses. From such facts the conclusion has been drawn that a given class of sensations may be produced by various stimuli. But the facts are not absolutely unambiguous. We do not know what constitutes an adequate stimulus in any case ; and we do not know what modifications the external stimu- lus undergoes before the final effect is produced. It may be, then, that a given class of sensations has only one adequate stimulus, and that, in the cases referred to, this adequate stimulus is produced in an unwonted manner. The pressure of the eyeball might cause a sensation of light, by setting the ether in the eye in vibration. Elec- tricity might work equally indirectly ; producing in the nerves those changes which are the proximate stimuli of their appropriate functions. It is at least conceivable that given sensory impulses are aroused only by stimuli of a special character, and that the action of irregular stimuli consists in producing the adequate stimulus in an extraordinary manner. The point admits of no positive decision. Sensations differ in quality to such a degree as to fall into completely incommensurable classes. The sensations of sound, light, pressure, odor, warmth, etc., have nothing whatever in common, except that they are all affections of the sensibility. There is no possibility of regarding them as multiples of a common unit. But for the differences of effects there must be some difference in the cause. We may seek for this difference, (1.) in the external stimuli, 44 PSYCHOLOGY. (2.) in some specific energy of the nerves, and (3.) in the form of nervous action. 1. The external stimulus falls into different classes, as air- and ether-waves, mechanical pressure, and chemical action ; but this difference of stimulus becomes significant only as it produces difference of nervous action. It is, however, far from plain that the peculiarities of the stimu- lus pass over into the nervous action, so as to found the absolute difference of sensations ; e. g., the enormous differ- ence of velocity between waves of light and those of sound disappears from the wave of molecular movement trans- mitted along the nerves. ■ 2. The most natural supposition would be, that each nerve has some specific peculiarity, whereby it becomes the sufiicient ground of the corresponding sensation. If such a difference were admitted, a reason would be given for the difference of sensations, and for the fact that a given nerve seems to respond to all stimuli only with its appropriate sensation. Of course, the simple fact that a certain nerve is the auditory nerve would contain no explanation of auditory sensations; there must be some difference of structure to found its specific qualities. For a long time this view was held, under the name of the specific energy of the nerves. However, anatomy reveals no difference of nerve structure on which to base the dif- ference of function, and hence the doctrine has been largely abandoned, or at least greatly limited. The essential ele- ments of all nerves, motory and sensory alike, seem to be the same ; and now it is sought to account for the differ- ence of function by difference of connection. In that case, the nerves would be like the wires of an electric battery, which do various kinds of work according to their con- nections at either end, and not according to any specific difference of structure in the wires themselves. Connected with a telephone, they send out one set of signals; con- SENSATION. 45 nected with a Morse instrument, they send quite another. Again, the effect of a current will vary also with the connections at the other end, producing ticking, articu- lations, incandescence, explosion, etc., according to the circumstances. 3. On this view, we must have the ground of the peculiar action of special nerves at one end or the other, or at both. In the case of the special senses we find a series of peculiar mechanisms for the reception and working over of external stimuli, and these seem fitted to give the action a peculiar form, which might serve as the ground of the sensational difference. Opposed to this is the fact that the optic nerve, if affected anywhere along its length, responds with a sen- sation of light. This would point to some peculiarity either of the nerve itself, or of its terminal structure or connection. The former view having been abandoned, we have only the latter left. And anatomy does reveal many peculiar structures in the brain ; and we might suppose that the nervous action, whatever its form, may receive here a new and final transformation, which first fits it to be the ground of sensation. We should in that case maintain the doctrine of a specific energy, not, indeed, of the nervous fibres, but of the central organ. But this view also has its difficulties. (1.) It ought to be possible to furnish persons born blind or deaf the sensations of light or sound, provided the trouble is due to some imperfection of the external organs ; but this does not seem to be the case. (2.) The view would demand an absolute constancy of function which does not exist. Many facts are reported which point to a vicarious action of the nerves, so that a given nervous tract can take upon itself the labors of another area upon occasion. On all these accounts, the tendency in physiology is toward the following view. The sensory nerves (omitting all reference to the motor nerves) have primarily no differ- 46 PSYCHOLOGY. ence of function ; and the ground of their actual difference lies originally in their peripheral endings and the stimuli to which they give access to the nerves. These endings, hovrever, give the nervous action a certain form ; and, as they condition nearly all the stimuli which reach the nerves, a given nerve is confined almost exclusively to one form of nervous action. Hence the nerve gradually adjusts itself to that form, and when disturbed at any point, or by any cause, it tends to take on that form, just as the wood of a violin tends to adjust itself to harmonious vibrations, and becomes more effective thereby. In this way a kind of acquired specific energy would arise, whereby, within cer- tain limits, a given nerve would remain faithful to its ac- quired modes of action. In this way we should explain the fact that sensations of light and sound remain possible long after the destruction of the external organs. But while the tendency is toward this view, it cannot be re- garded as universally accepted. It is still held by many, that certain fibres in the ear are sensitive only to certain tones, like the strings of an instrument, and that different sets of visual fibres correspond to the three colors green, red, and violet. The other colors are supposed to arise from the varying activities of these fibres. Others agree in af- firming differences of function in the optical fibres, but dif- fer in their conception of the basal colors. It is not always easy, however, to see how these views serve the purpose of their invention. The facts of color-blindness would find an easy explanation in them ; but it is not clear how blue or yellow is to arise from a simultaneous excitation of the fibres which produce green, red, and violet. It is plain from the foregoing, that concerning the par- ticular form of the nervous action nothing can be known. To what extent the original vibration of the ether is modified in the retina, and in its passage through the central organs of vision, is beyond all suspicion. Our current physical SENSATION. 47 science, however, leaves us no choice but to regard the action as some form of movement ; and as vibrations are always fashionable, we may view it as a species of vibration. We might in that case assume that the difference of sensa- tions depends upon the difference in these vibrations. They might be conceived as longitudinal, or transverse, or as moving in closed orbits and with different velocities. Leav- ing such fancies to themselves, we may point out that sim- ple movements of matter, of whatever sort, can never be a sufficient ground of sensation. Such movements are simply a passage of one or more elements from one point to an- other ; and there is no way of connecting them with mental changes except by supposing that there is a deeper dynamic relation which is the real ground of the sensation. Indeed, metaphysics convinces us that, even in the physical world, the spatial system of changes among things is really only the visible translation of a metaphysical system of inter- action in things. Things do not act on one another because they move, but they move because they act on one another. It is not the fact that the nerve molecules vibrate which fits them to the ground of sensation, but the fact that they are in dynamic relations with the soul. The sensations, there- fore, are not to be referred to the vibrations, but rather to that internal energy of which the vibration is the spatial expression. But since tlie relation between the inner en- ergy and the spatial expression is regarded as constant, we may take the latter as the equivalent of the former, and continue to speak of vibrations as the ground of sensation. This conception of nervous action implies that all ante- cedents of sensation can be conceived as phases of a com- mon process, so that by varying the common factors we might pass through the entire series. By modifying ve- locity and direction any form of vibration might be made to pass into any other whatever. In that case, all sensory impulses might be arranged on a scale like the colors of 48 PSYCHOLOGY. the spectrum or the notes of music. But such an order would lead us to expect a corresponding community in the members of the sensational series and the possibility of arranging our sensations on a common scale. Such a fact, however, does not exist. It is not always easy to find a common element in the sensations of the same nerve, e. g. the optic nerve ; and it is impossible to find any common feature in the data of the different senses, or any possibility of passing from one to the other by intermediate gradations. Such a possibility may exist on the physical side, but it does not exist on the mental side. In a later paragraph we shall refer to the attempt to reduce our sensations to a common sensational unit. Our complete ignorance of what takes place in the nerves is no psychological loss. For practical purposes, we should be no wiser if we had the profoundest insight into the action of the external stimulus ; and psychologically, also, we should be no better off if we knew all about the form of the nervous action in any special experience, and the place of its location. The ability to locate and describe every sensory and motor process would only give us an exact knowledge of the physical antecedents of sensation, but would bring us no nearer to comprehending how they pro- duce sensations, or how sensations are worked over after they are produced, or even what the sensations are. Indeed, the facts with which we have been dealing arc not properly psychological facts at all. The idealist, of course, would deny that they are facts of any kind. Another question of considerable interest, but of about as little psychological significance, concerns the relation of the intensity of the sensation to that of the stimulus. Sensations diif er in quality, and thereby are distinguished into different classes. Sensations of the same class differ in intensity, and the commonest experiences show that this varies with the stimulus. In seeking for the relation bo- SENSATION. 49 tween the intensity of sensation and nervous action, it is, of course, impossible to observe the nervous action which immediately precedes the sensation, and it only remains to study the relation between sensation and the exter- nal stimulus. Several difficulties may be mentioned in advance. 1. The distinction of intensity itself is generally a quali- tative as well as a quantitative one, and in most cases it is due to an unwillingness to multiply classes beyond neces- sity. In fact, the sensations of the same class, which, out of respect for established classification, we regard as differ- ing only in intensity, differ also in quality. Hence, a vary- ing intensity of the stimulus often produces, not a more intense sensation, but a different one. Increase of pressure, heat, light, or intensity of flavor or odor results in sen- sations of different qualitative nature. Cold is not a faint sensation of warmth ; and a burn is not an intensified glow of comfort. A given flavor diluted may have a pleasing taste ; concentrated, it may be utterly disgusting. Yet it would hardly do to call the disgust intensified pleasure be- cause the stimuli in the two cases differ only in intensity. It is only in the case of sounds that we can distinguish with any certainty a quality (the pitch) which remains the same tlu'ough all variations of intensity. 2. The effect never depends entirely upon the external stimulus. The state of the nervous system, the amount of expectation and attention, the continuance of effects in the nerves after the stimulus has been removed, are all to be taken into account. An exhausted nerve responds with diminishing vigor. An excited nerve, especially the optic nerve, continues to produce sensation after the stimulus is removed. After-images, the vision of complementary colors, and the temporary blindness after looking at the sun, are examples. Sensations of temperature, on the other hand, depend, within certain limits, altogether on the direction of 4 50 PSYCHOLOGY. change ; so that the same absolute temperature may be felt as either hot or cold, according to circumstances. These difficulties would be fatal, if the aim were to find a fixed connection between a given intensity of stimulus and a given intensity of sensation. Discounting such high claims, we may glance at what has been done in this field. It is easy to arrange a series of stimuli of a given class on a numerical scale, so that their relative intensity can be seen or calculated. It is equally easy to observe the re- sulting sensations, but it is not possible to arrange their intensities on a numerical scale. We have, indeed, a fine sense for more or less, but we cannot tell how much more or less. We find no sensation of which we can say that it is just twice as strong as another. If this were possible, our task would be easy. We should only need to compare the numerical scale of the resulting sensations in order to get the law of their connection. But since this is impossible, we must adopt some indirect method. E. g., we may take some stimulus of measured intensity, and increase or decrease it gradually, and note the point at which an increase or decrease of sensation is perceptible. The process may be repeated in either direc- tion, and thus we may get the following scale : S, Si, S2, S3, Si, S^, Sq, S^; a, ai, «2? <^37 <^4j %) ^6? ^D.'f where S, etc. represent the just distinguishable sensa- tions, and a, etc. represent the stimuli. The series a, ai, etc. may be a series of weights ; and S, Si, etc. may be a series of just distinguishable sensations of weight. We should find that the same increase of stimulus which pro- duces a feeling of change in the lower members of the series does not suffice to produce such feeling in the higher members ; e. g., we can easily distinguish between one and two ounces, but not between ten pounds and ten pounds SENSATION. 51 and one ounce. Or we can see at once that a two-inch line is longer than a one inch line, but not that a line fiftj^-one inches long is longer than another of fifty inches. In order to produce a sense of difference, the increase of stimulus must bear some general proportion to the stimulus itself. E. H. Weber, who first broke ground in this matter, declared the law to be, that the increase of the stimulus must be a fixed proportion of the stimulus ; e.g., if, holding a pound weight, I must add an ounce in order to perceive a difference, then, holding a two-pound weight, I must add two ounces before any difference is perceived. In like manner, n pounds must be increased by n ounces to pro- duce a sense of difference. This ratio is different for the different senses, being about 3 : 4 for the ear and feelings of pressure, 15 : 16 for muscular sensations, and 100 : 101 for the eye. We should also find that, below a certain point, there would be no sensation. This point is called the " threshold," and determines the absolute sensibility of the nerve in question. The constant fraction which must be added to produce a feeling of difference determines the discriminative sensibility. The formula we have given is known as Weber's law, and the method described was employed by Weber himself, and is known as the method of smallest perceptible differ- ences. Besides this, various other methods are employed for the same purpose of establishing a relation between the intensity of the sensation and the stimulus, but they add nothing to the result. The law itself is valid only within narrow limits. It does not hold at all for some classes of sensations, and is invalid for others whenever the stimulus is very large or very small. This empirical law has been transformed by Fechner, so as to express the numerical relation between the variation of the stimulus and that of the sensation. Recurring to the two series, 52 PSYCHOLOGY. S, Si, S2, S2, /S'4, s^, a, «!,