TWO ANATOMICAL EXERCITATIONS Concerning The Circulation of the Blood, To John Riolan the Son, the most experienced Physician in the university of Paris, the Prince of Dissectors of Bodies, and the King's Professors and Dean of anatomy, and the knowledge of Simples; Chief Physician to the Queen-Mother of Lewis XIII.  
The Author, WILLIAM HARVEY, an Englishman, Professor of anatomy and chirurgery in the College of Physicians at LONDON, and Doctor of physic to the Kings most Excellent majesty.  
London, Printed by Francis Leach, 1653.   


The First ANATOMICAL EXERCITATION Concerning The Circulation of the Blood, To JOHN RIOLAN.  
THere did come forth not many months ago a little piece of the most famous Riolan's, concerning anatomy and Diseases; for which, as being sent to me by the Author himself, I return hearty thanks: Seriously I do congratulate the felicity of that man in undertaking a thing very commendable. To open to the view the seats of all Diseases, is a work not to be achieved but by a divine wit; Truly he undertook a hard task, that has set those Diseases, which are almost obscure to our understanding, before our eyes. Such endeavours become the Prince of Anatomists; for there is no Science which has not its beginning from foregoing knowledge, nor any knowledge which is not beholding to sense for its original: For which cause the business itself, and the example of so worthy a person required my pains, and did invite me in like manner to put forth and join my medicinal Anatomic, being chiefly fitted for Physical uses, not with the same intention as he, by demonstrating the places of diseases, from the dead bodies of healthful men, and rehearsing the divers sorts of diseases incident to those places, according to other men's opinions, which he ought to have seen there; but that I might undertake to relate from the many dissections of sick bodies, and the most grievous and wonderful diseases of dead persons, in what manner, and how the inward parts of them are changed, in place, bigness, condition, figure, substance, and other sensible accidents, from their natural form and appearance, which all Anatomists commonly described, and how diversely and wonderfully they are affected. For as the dissection of healthful and well habited bodies conduces much to philosophy and right physiology, so the inspection of diseased bodies conduces chiefly to Pathological philosophy. For the Physiological contemplation of those things which are according to Nature, is first to be known by the Physician, for that which is according to Nature is right, and is rule both to itself and that which is amiss; by the light of which, errors and preternatural diseases being defined, pathology is more clear, and from pathology the use and art of administering physic, and occasions of inventing many new remedies do ocur. Nor will any man believe how much in diseases, especially such as are Chronical, the innards are changed, and what monstrous shapes of the inward parts are begotten by diseases: And I dare say the opening and dissection of one consumptive person, or of a body spent with some ancient or venomous disease, has more enriched the knowledge of physic, than the dissections of ten bodies of men that have been hanged.  
Yet do not I disallow of the most famous and most learned Anatomist Riolan his purpose, but think it highly to be commended, as being very profitable for physic, that he does illustrate the Physiological part; yet did I think that it would not be less profitable to the art of physic if I should set clearly before your eyes to be seen, not only the places, but likewise the diseases of those places, and rehearse them, after I had well viewed and observed them, and from my many dissections declare my experience.  
But such things in that Book concerning the Circulation of the blood found out by me, which are translated, and seem to reflect only upon me, must first and chiefly be taken into consideration by me. For so great a man's judgement, concerning such a weighty business, is not to be set at nought (who is undoubtedly thought the chief, and ringleader of all Anatomists of this age) but the opinion of him alone, is more to be weighed for commendation, than the verdicts of all others, which shall either applaud or contradict me, and his censure more to be weighed and looked upon. He then in his lib. 3. cap. 8. Enchir. acknowledges our motion of the blood in Animals, and takes part with us, and is of our opinion, as concerning the circulation of the blood: yet not altogether, and openly; for he says, lib. 2. cap. 21. That the blood in the port vein contained, admits no circulation, as the blood in the vena cava, and in lib. 3. cap. 8. That there is blood which is circulated, and circulatory vessels, to wit, the aorta and the vena cava, yet he denies that the branches of them have any circulation; Because, says he, the blood running out into all the parts of the second and third region, stays there for nutrition, nor does it flow back to the greater vessels, but being plucked back by force, when the greater vessels are in great want of blood, or when it returns with a sudden force, or exstimulation, to the greater circulatory vessels. And so a little after. Whether or no the blood of the veins, does perpetually or naturally ascend, or whether it returns to the Heart, or Whether the blood of the Arteries do descend, or go from the Heart, yet if the lesser veins of the arms and legs be empty, the blood of the veins in succession filling the empty places, may descend, which (Says he) I have clearly demonstrated against Harvey and Wallaeus. And because daily experience and the authority of Galen does comfirm the Anastomosis of the veins & arteries, & the necessity of the Circulation of the blood; You see, says he, how the circulation of the blood comes about, without the confusion of humours, or the perturbation of ancient medicine.  
By which words it is known, for what cause the most famous man would partly acknowledge, partly deny the Circulation of the blood, and why he endeavours to build a reeling and tottering opinion of Circulation. Lest, forsooth, he should destroy the ancient physic, and not moved by truth, which he could not choose but see, but rather for fear he should violate the ancient rules of physic, or perchance, lest he ssould seem to resume or retract that physiology which in his Anthropologia he had published before. For the Circulation of the Blood does not destroy the ancient physic, but furthers it; rather it show the physiology of Physicians, and the speculation of natural things, and disallows the Anatomical doctrine of the use and action of the heart, lungs; and the rest of the entrails; and that these things are so, will appear partly out of his own words, partly out of those things which I shall here set down; namely, that the whole blood, in whatsoever part of the body living it be, does move and shift place (as well that which is in the greater veins, and their branches and fibers, as that in the porosities of the parts in any region of the body) does flow to the heart, & flow from the heart, without interruption, incessantly, and never continues in one place without damage; though I do not say, but in some places it moves flower, in some faster.  
First then, the most learned man denies only that the blood contained in the Porta does circulate, which he could neither have denied nor disapproved of, if he had not passed over the force of his own argument: for he says lib. 3. cap. 8. If in every pulsation the heart receive one drop of blood, which it expels into the aorta, and does make two thousand pulsations in an hour, there must needs a great deal of blood pass through. He is likewise forced to affirm the same of the mesentery, since through the caliacal artery, and the mesenterial arteries, there is thrust in more than one drop of blood at every pulsation, and is forced against the mesentery and its veins: insomuch that it must either go out according to the just proportion of that which enters, otherwise the branches of the Porta would burst at last; nor can it (for the resolution of this doubt) be probably said, or possibly be, that the blood of the mesenteric should vainly, and to no purpose, ebb and flow through these arteries, like an Euripus; nor the relapse from the mesenteric by those passages and transplantation by which he would have the mesenteric disgorge itself into the aorta, likely to be true; nor can it prevail against that which is entering by contrary motion; nor can there be any vicissitude, where it is most certain that without interruption, and incessantly, there is an influx; but is compelled by the same necessity, by which it is certain, that the heart doth thrust forth the blood against the mensenterium. Which is most manifest; for otherwise, by the same argument, they would overthrow all Circulation of the blood, if thus he should, with the same likelihood of truth, affirm that too in the ventricles of the heart, namely in the Systole of the heart the blood is driven into the aorta, and in the Diastole returns, and the aorta disburthens itself into the ventricles of the heart, as the ventricles again into the aorta, and so neither in the heart nor in the mesentery should there be any circulation, but a flux and reflux, by turns, is turned up and down with needless labour: Therefore if of necessity in the heart is proved the circulation of the blood, for the reason aforesaid proved by himself, the same force of argument takes place likewise in the mesentery; but if there be no circulation in the mesentery, neither is there in the heart; for both these assertions, namely, this of the heart, that of the mesentery, hangs upon the force of the same argument, only changing the words, and is established, and falls in like manner.  
He says, that the Sigma-like portals do hinder the regress of the blood in the heart, but there are no portals in the mesentery.  
I answer, neither is this true; for in the splenick branch, as likewise sometimes in others, there are found portals. Besides, portals are not all times requisite in the more profound veins, nor are they found in the deep veins of the joints, but rather in the skin veins; for where the blood flowing out of the less branches is prone naturally to come into the greater, by the compression of the muscles about it it is sufficiently hindered from return, but where the passage being open, it is forced; What need is there there of portals? But how much blood at every pulsation is forced into the mesentery, is reckoned according to the same account, as if with an indifferent ligature you should in the carpus bind the veins coming out of the hand, and entering into the arteries; (for the arteries of the mesentery are greater than those of the carpus) if you tell at how many pulsations the vessel and your whole hand swell to their greatest biguesse dividing and making a subduction, you shall find much more than one drop of blood come in at every pulsation, notwithstanding the ligature; nor can it return, but rather that in filling the hand it forcibly distends and swells it, we may by calculation gather, that the blood enters the mesenteric in the same quantity, if not in a greater, by how much the arteries of the mesenteric are greater than those of the carpus. And if any should but see and think with himself, with what difficulty and pains, compressions, ligatures, and several means the blood is stayed, that leaps forcibly out of the least artery which is cut or broken, with what strength (as if it were shot out of a spout) it throws off, and drives away, or passes through all the bindings, I think he would scarce believe that any part of blood which only enters, could against this impulsion and influx pass back again, being not able to drive it back with force. For which cause, considering these things with himself, I believe it would not ever enter his mind to imagine that the blood out of the veins of the porta could creep back by these same ways, and so disburden itself into the mesentery, against so forcible and strong an influx into the arteries.  
Moreover, if the most learned man believe not that the blood is moved and changed by circular motion, but being still the same, it stands and mantles in the branches of the mesentery; he seems to suppose, that there is a twofold blood, divers, and serving to divers uses and ends, and therefore it is of divers natures in the vena porta and cava, because one of them for its preservation needs circulation, the other needs not, which neither does it appear, nor does he demonstrate it to be true.  
Besides the most learned man adds in his Enchirid. lib. 2. cap. 18. A fourth sort of vessels to the mesentery, which are called the Venae Lacteae (invented by Asselius) which being set down, he seems to infer that all the nutriment being drawn through them is carried to the liver, the forge of blood, which being there concocted and changed into blood, (he says in lib. 3. cap. 8.) it is carried to the left ventricle of the heart, which being granted, says he, all the scruples which were anciently motioned concerning the distribution of the Chylus, and of the blood through the same conduit, do cease, for the Venae Lacteae carry the Chylus to the Liver, and therefore these conduits are apart, and can be obstructed apart. But indeed I would fain know how this can be demonstrated to be true; If this milk be transfused and pass into the liver, how shall it get thence through the cava into the ventricle of the heart? (Since the most learned man denies that the blood contained in the numerous branches of the porta and the liver can pass, that so circulation may be made) but more especially since the blood seems to be a great deal fuller of spirit, and more penetrative than the milk or chylus, which is contained in these vessels, and is hitherto impelled by the arteries that it may find out some way for its self.  
The most learned man makes mention of a certain Treatise of his concerning the Circulation of the blood, I wish I could see it, I might perchance recant.  
But if the most learned man thought it more fit to place the circular motion of the blood in the veins of the porta, and branches of the cava, (as he says in his 3. Book Chap. 8. In the veins the blood does perpetnally and naturally ascend or return to the heart, as likewise that which is in all the arteries descends and departs from the heart. I say, I do not see, but upon this position all difficulties which were objected of old of the distribution of the Chylus, & blood, through these same conduits, should likewise cease, that hence forward he should not need to inquire apart for, or to set down vessels for the chylus; seeing as the Umbilical veins do draw their nutritive juice from the liquours of the egg, and carries it to the nourishing and augmentation of the Chick whilst it is yet an Embryon, so do the meseraic veins suck the chylus from the intestines, and carry it to the liver, and what hinders us to assert, that it does the like in those of riper age? for all difficulties cease, when there are not two contrary motions supposed in the same vessels; but that we do suppose that there is one continued motion in the mesenterics from the intestines to the Liver.  
I shall tell you in another place what is to be thought of the venae Lacteae, when I shall speak of milk found in several parts of creatures new born, especially in mankind, for it is found in the mesentery and all its glandules, as also in the chymus, likewise in the armpits and paps of Children; the midwife's milk out the blood for their health as they believe.  
But moreover it pleased the most learned Riolan, not only to deprive the blood contained in the mesentery of circulation, but also he affirms, that neither the branches of the vena cava, or its artery, or any part of the second or third region admits of circulation, so that only he calls the vena cava & the aorta circulatory vessels, for which in his 3 Book Chap. 8. he gives a very faint reason, Because the blood, says he, flowing into all parts of the second and third region remains there for nourishment nor does it flow back to the greater vessels, unless it be revulsed by the force and want of blood in the greater vessels, or flow back, being stirred with a sudden force, to the circulatory vessels.  
It is indeed of necessity, that the portion which passes into nourishment, should remain, for otherwise it should not nourish unless it be assimilated, & stay there, in lieu of that which is lost, & so become one: but it is not needful, that the whole influx of blood should remain there for the conversion of so little a portion; for every part does not use so much blood for its nourishment, as it contains in its veins, arteries, and porosities, nor is it necessary in his afflux and reflux that it should leave no nourishment within it; where fore it is not necessary that for nutrition it should all stay, but likewise the most learned man himself, in the very same book in which he affirms this, does seem everywhere almost to affirm the contrary, especially where he sets down the circulation in the brain, and by circulation (Says he) the brain does send back blood to the heart, and so the heart is refrigerated. After which sort likewise, the remote parts may be said to refrigerat the heart, whence also in fevers, when the parts about the heart are grievously scorched and inflamed with feverish heat, laying naked their joints, and throwing off the clothes, sick people endeavour to cool their heart, whilst (as the most learned man affirms of the brain) the blood being refrigerated and allayed of its heat, does then go to the heart through the veins, and does refrigerat it. Whence the most learned man seems to insinuate a kind of necessity, that as from the brains, so there is a circulation from all the parts, otherwise than before he had openly declared. But indeed he cautiously and ambiguously affirms. That the blood does not flow back from the parts of the second and third region, unless, says he being revulsed by the force and great want of blood in the bigger vessels, or that it does by a sudden forcible motion flow back to the greater circulatory vessels, which is most true, if these words be understood in a true sense; for by the greater vessels, in which he says want causes a reflux. I believe he understands the vena cava, or the circulatory veins, not the arteries; for the arteries are never emptied, but into the veins, or pores of the parts, but they are continually stuffed full by the pulse of the heart. If all the parts did not incessantly refund blood in abundance into the vena cava, and the circulatory vessels, out of which the blood very suddenly passes, and hastens to the heart, there would quickly be a great want of blood. Besides that, the blood which is contained in all the parts of the second and third region, by the force of the blood directed and driven by every pulse, is foreed out of the pores into the veins, out of the branches into the greater vessels, as likewise by the motion and compression of the parts adjacent; for that which is contained is thrust out by every thing containing it, when it is pressed and straightened: so by the motion of the muscles and the joints, the branches of the veins passing between being pressed and straightened, thrust the blood contained in the lesser vessels into the greater.  
But it is not to be doubted, that the blood is continually and incessantly driven, and comes with force from the arteries, and never flows back; if it be admitted, that in every pulse all the arteries together are distended by the propulsion of blood, and that the Diastole of the arteries, as the most learned man confesses, is from the Systole of the heart; nor does the blood once gone forth, return into the ventricles of the heart, by reason that the portals are shut, if (I say) the most learned man do believe these things, as it seems he does, it will easily be understood in every part of what region soever, by what stuffing or impulsion the blood in them contained is forcibly thrust down.  
For so far as the arteries beat, so far reaches the influx and the force, wherefore it is felt in all parts of every region, for there is a pulse everywhere in the tops of our fingers, and under the nails, nor is there any part in our whole body, either sore with boil or felon, which does not feel the pricking motion of the beating of the artery, and its endeavour to dissolve the continuum.  
But further it is manifest, that the blood does make a regress in the pores of the parts, in the skin of the hands and feet, for sometimes in great frost and cold seasons we see the hands and joints, especially of boys, so cold, that at the very touch they do almost resemble the coldness of Ice, and are so benumbed and stiff, that there is scarce any life in them, nor motion, and yet in the mean time they are full of blood seeming red or blue, which parts can again by no means be warmed, unless by Circulation that refrigerate blood be thrust out, and in its place, new, warm, and spirituous blood flowing in do foment and rewarm the parts, and restore to them motion and sense; for they should never be renewed or restored by external heat, no more than the members of dead persons, unless some internal influent warmth did refresh them. This indeed is the chief use & end of the Circulation of the blood, for which cause, the blood by its continual course, and perpetual influence, is driven about; namely, that all the parts depending upon it by their first innate warm moisture might be retained in life, and in their own vital and vegetative essence, and perform all their functions, whilst (as the naturalists say) they are sustained and actuated by natural heat, and vital spirits; so by the help of two extremities, heat and cold, the temper of the bodies of creatures is kept in its mediocrity: for as the breathing in of air does temper the too much heat of the blood in the lungs, and in the centre of the body, and causes the eventilation of suffocating fumes; so also the blood being hot, and cast out through the arteries into the whole body, does foment and nourish the extremities in living creatures and hinders them to be extinguished by the force of outward cold.  
Therefore it were injust and wonderful, if every little part of what region soever should not enjoy the benefit of the transmutation and circulation of the blood, for whose sake Circulation seems chiefly to be appointed by Nature. Therefore, that I may conclude, for you see how the Circulation of the blood is performed without perturbation or confusion of the humours, in all the body, and in every part, both in the greater and in the lesser vessels, and that by necessity, and for the benefit of all the parts, without which, being cold and impotent, they could never be restored, or remain alive. It is enough, because its clear, that all influence of preservative heat does come through the arteries, and is done by circulation.  
For which cause most learned Riolan seems to me, when he says, that in some parts there is no Circulation, to speak rather officiously, than truth; to wit, that he might please most men, and oppose nobody, and that he rather wrote humanly, than gravely, in the behalf of the truth. As he likewise seems to do (lib. 3. cap 8.) when he would rather have the blood to come into the left ventricle through the septum of the heart, through uncertain and hidden passages, than through the large and most open vessels of the lungs, being made with Portals artificially to hinder its return. I desire to see the reason of the impossibility and inconvenience which he says he propounded elsewhere. It is a wonder, since the Aorta and vena Arteriosa, are of the same bigness, constitution, and frame, that their function should not be the same. But that is very improbable that the great River of the whole mass of blood should in so great abundance go into the left ventricle by so blind and small a winding of the septum, which should answer both to the entry from the vena cava in the right side of the heart, and also its egress from the left, which do both require such wide orifices. But he has likewise produced these things staggeringly, for in lib. 3. ca 6. he ordains the lungs as a sink or passage from the heart, and he says, The lungs are affected by that blood which passes through, whilst its filth flows together with that blood; so he says likewise, That the lungs acquire corruption by distempered, and ill-condition'dintralls, which furnish the heart with impure blood, whose fault the heart cannot help, but by many circulations. He likewise in the same place, concerning letting of blood, and shortness of breath, & communication of the veins with the vessels of the lungs, says against Galen, If it be rue that the blood does naturally pass from the right ventricle of the heart to the lungs that it may be carried to the left ventricle, and so to the aorta; and if the Circulation of the blood be admitted, who sees not in the diseases of the lungs, that the blood flows thither in greater abundance, and oppresses the lungs, unless they be first largely emptied, every part taking a share to case them; which was Hippocrates advice, from all parts of the body, head, nose, tongue, arms, feet, to take away the blood, that the quantity of it might be impaired, and that it might be revulsed from the lungs, and so draws out the blood till the body was quite without blood. He says likewise, The Circulation being supposed, the lungs are easily emptied by breathing a vein. If this counsel be rejected, I see not how it can be revulsed from thence; for if it flow back through the vena arteriosa into the right ventricle, the Sigmoidal portals hinder it, and the three-pointed portals hinder the regress out of the right ventricle into the vena cava. Therefore by Circulation the bload will be exhausted, by cutting the veins of the arms and feet. And likewise Pernelius his opinion in the affections of the lungs is destroyed, that blood is rather to be taken out of the right arm than out of the left, for the blood cannot return into the vena cava, unless it break through two gates and bars which are placed in the heart.  
He adds moreover in the same place, (lib. 3. cap. 6.) If the Circulation of the blood be admitted, and that it doth pass often through the lungs, and not through the middle of the Septum of the heart, there is a twofold Circulation of the blood to be assigned, one of which is perfected by the heart and the lungs, whilst the blood leaping out from the right ventricle of the heart is carried through the lungs, that it may come to the left ventricle of the heart; for leaping out from the same inward part, it returns to it, then by another larger circulation flowing out of the left ventricle of the bear't, it goes about the whole body, and runs through the arteries and veins to the right ventricle of the heart.  
The most learned man in this place might have added the third circulation, which is a very short one, out of the left ventricle into the right, drawing about a part of the blood through the coronal arteriese and veins, by its branches, which are distributed about the body, walls, and septum of the heart.  
He says, He that admits of one circulation, cannot deny the other. So might he have added, nor can he refurse the third. For to what purpose should the coronal arteries beat in the heart, if they did not drive blood thither? and why should the veins, (whose function and end it is to receive blood put into them by the arteries) but that they might draw blood from the heart? Moreover in the orfice of the Coronal artery (as the learned man himself confesses, in his third Book and his ninth Chapter,) there is a portal which forbids, all entrance, and is patent to egress: therefore truly he cannot but admit of the third Circulation, who likewise admits of another universal one, and that the blood does likewise pass through the lungs and the brain, (lib. 4. cap. 2.) For neither can there be an admittance of blood by pulsation, in all parts of every region, nor regress by the veins after the same manner, and therefore he cannot deny, but that the parts admit of Circulation.  
Therefore it is clear from these very words of the most learned man, what his opinion is, both of the Circulation of the blood through the whole body, as likewise through the lungs and the rest of the parts; for the that admits of the first Circulation, it is clear that he does not reject the other: For how can it be, that he who has admitted of another Circulaon through the whole body so often, and through the greater circulatory vessels, should deny that universal Circulation in any of the branches or parts of the second or third region? As if all the veins & those greater circulatory vessels, as he calls them, were not numbered by himself, and by all others, amongst the vessels of the second region. Is it possible that there should be circulation through the whole body, and not through all the parts? and therefore where he denies it he does it very stammeringly, and only staggers and palliates in his negations; there where he affirms he speaks understandingly and as becomes a Philosopher, and as a skilful Physician and an honest man, gives his advice in this case, that in the dangerous diseases of the lungs the letting of blood is the only remedy, against Gales and his beloved Fernelius: in which thing if he had been doubtful, far be it from a Christian and so learned a man, to recommend his expements to posterity, to procure death, and the hazard of men's lives, or that he should recede from Fernelius or Galen, men in high esteem with him. Therefore whatsoever he has denied of the Circulation in the mesentery, or any other part, in favour of the ancient Doctrine of physic, or the Venae Lacteae, or for any other regard, it is to be attributed to his civility and modesty, and to be prdoned.  
I think it does already appear clearly enough, both from the words and the arguments of the most learned man himself, that there is a circulation everywhere, and that blood wheresoever it is, does change place, and pass through the veins to the heart; and the most learned man seems to be of the same opinion with me; Therefore it needs not, yea it were superfluous to bring hither my arguments which I have published in my Book concerning the motion of the blood, for the further confirmation of this truth, which are taken both from the frame of the vessels, placing of the portals, and other experiments and observations; especially since I have not as yet seen the most learnedd man's Treatise of the Circulation of the blood, nor as yet any of the most learned man's Arguments, but only a bare negation, by which being induced he should reject the circulation in the regions and vessels, which he allows to be universal in most of the parts.  
It is indeed true, that I did find out of the authority of Galen, and by daily experience to be a refugium the Anastomosis of the veslels, yet so great a man as he is, so diligent, so curious, so expert an Anatomist, should first have laid open and shown anastomosis, and those visible and open ones, and whirlpools proportionable to the imperuous stream of the whole blood, and the orifices of the branches, (from which he has taken away circulation) before he had rejected those which were most probable and most open. He was obliged to demonstrate and declare where they are, how they are framed, whether they are not only fit for the intromission of blood (as we see the arteries inserted in the bladder) and not for the return of it, or what other way soever they had been. But perchance I speak too boldly for neither the learned man, nor Galen himself, could by any experience ever behold the sensible anastomosis, or ever could demonstrate them to the sense.  
I did look after them with all possible diligence, and was not at a little charge and pains in the search of the anastomosis, yet could I never find that any vessel, namely the arteries, together with the veins, were joined by their orifices: I should willingly learn from others who ascribe so much to Galen, that they dare swear all which he says. Nor is there any Anastomosis in the liver, milt, lungs, reins, or any other of the entrails, although I did boil them till the whole Parenchyme was made mouldering, and like dust was shaken off, and taken away with the point of a needle, from all the fibers of the vessels, so that I could see the fibers, and the last grains of every division. I dare therefore boldy affirm, that neither the vena porta has any anastomosis with the cava, nor the veins with the arteries, or the capillar branches of the poor of the chollerbagg, which are dispersed about all the flat of the liver with the veins. Only this you may observe in a fresh liver, that all the branches of the vena cava which creep through the whole bunch of the liver, have tunicles pierced with many holes like a sive, as it is in a sink, framed so for the receiving of the blood which falls down. The branches of the Porta are not so, but are divided into stems, and how that both the divisions of these vessels, the one in the flat, the other in the gibbous part, do run round to the very furthest rising of that intrall without any anastomosis.  
Only in three places do I find that which is equivalent to an Anastomosis. There rises in the brain, from the soporall arteries creeping down into the Basis, many and unintangled fibers, which afterwards make up the plexus chorois, and passing through the ventricles do at last end in the third receptacle, which performs the office of a vein. In the spermatical vessels, commonly called preparatory, little arteries drawn from the great artery do adhere to the veins preparatory aforesaid, which they accompany, and at last are so received within their Tunicle, so that at the first they seem both to have one and the same, so that when they end at the upper part of the testicles where that part passes forth into a point, which is called the varicous and vine-like body, we know not what to call them, veins or arteries, or the ends of both. As likewise the last appearances of the arteries which go to the umbilical vein, are obliterated in the Tunicles of that vein.  
What doubt is to be made, if through such gulfs, the little branches of the arteria magna, swollen with the impulsion and instuffing of blood, could be eased of so great and so conspicuous a stream? Nature at least would never have denied us visible and sensible passages, sinks and whirlpools, if she had had intention to have turned all the flux of the blood thither, and by that means have deprived the lesser branches, and the solid parts of the benefit of the influx of blood.  
Lastly, I will set down one experiment, which seems to be sufficient for the clearing of the anastomosis, and for the overthrowing of their use, and of the passage of the blood, and return of it out of the veins into the arteries, by those ways.  
Opening the breast of any creature, and tying the vena cava by the heart, so that nothing can pass that way into the heart, and presently cutting the jugular arteries, not touching the veins on neither side, If by giving vent you see the arteries emptied, and not the veins too, I hope it will be clear that the blood is carried out of the veins into the arteries, nowhere but through the ventricles of the heart. Otherwise (as Galen has observed) in a little space we should see the veins emptied, and destitute of blood by the efflux of the arteries.  
In what remains, Riolan, I both congratulate myself and you, myself for your opinion, with which you have adorned my Circulation, as likewise I return to you exceeding thanks for your learned, neat, succinct piece which you sent to me, than which there is nothing more elegant, and I both owe and desire to return deserved commendation, but I confess I am not able for such a charge. For I know the name of Riolan will afford more praise to me in its subscription, than my praises, which I wish as great as may be can do to his Enchiridion. The famous book shall outlive all memory, and shall recommend your worth to Posterity when all Monuments shall perish. To it you have very handsomely adjoined the Anatomy of Diseases, and have very profitably enriched it with a new Treatise concerning the Bones. May you, most worthy Man, continually increase in this your worth, and love me, who wish that you may be both happy and long lived, and that your most famous writings may be an eternal Commendation to you.  
William Harvey.   

ANOTHER EXERCITATION, TO JOHN RIOLAN.  
In which, many Objections against the Circulation of the Blood are refuted.  
MOst learned Riolan, by the help of the press, many years ago, I published a part of my labour: But since the birthday of the Circulation of the Blood, almost no day has past, nor the least space of time, in which I have not heard both good and evil of the Circulation of the Blood which I found out: Others rail at it, as a tender baby unworthy to come to light; Others say, that its worthy to be fostered and favour my writings, and defend them; Some with great disdain oppose them; Some with mighty appause protect them; Others say, that I have abundantly by many experiments, observations, and ocular testimony, confirmed the Circulation of the blood, against all strength and force of arguments; Others think it not yet sufficiently illustratted, and vindicated from objections: But there are who cry out, that I have affected a vain commendation in dissection of living creatures, and do with childish slighting dispraise and deride at Frogs and Serpents, Gnats, and other more inconsiderable creatures brought upon the Stage, and refrain not from ill language. But I think it a thing unworthy of a Philosopher and a searcher of the truth, to return bad words for bad words, and I think I shall do better and more advised, if with the light of true and evident observations I shall wipe away those symptoms of incivility.  
It cannot be eschewed but dogs will bark and belch up their surfeits; nor can it be helped, but that the cynics will be amongst the number of the Philosophers: but we must take a special care that they do not bite, nor infect us with their cruel madness, or lest they should with their dogs teeth gnaw the very bones or principles of truth.  
Detractors, Momes, and writers stained with railing, as I never intended to read any of them (from whom nothing of solidity, nor any thing extraordinary is to be hoped for, but bad words) so did I much less think them worthy of an answer: Let them enjoy their own cursed nature, I believe they will find but a few favourable Readers; neither does God give wisdom to the wicked, which is the most excellent gift, and most to be sought for: Let them rail on still, till they be weary (if not ashamed) of it.  
If you will enter with Heraclitus in Aristotle into a workhouse (for so I will call it) for inspection of viler creatures, come hithet, for the immortal gods are here likewise; and the great and Almighty Father is sometimes most conspicuous in the least and most inconsiderable creatures.  
In my book concerning the motion of the heart and blood in creatures, I only chose out those things out of my many other observations, by which I either thought that errors were confuted, or truth was confirmed; I left out many things as unnecessary and unprofitable, which notwithstanding are discernible by dissection and sense; of which I shall now add some in few words, in favour of those that desire to learn. The great authority of Galen is of so much account with everybody, that I see many make a difficulty as concerning that experiment of Galen of the ligature of the artery above the pipe, thrust within the concavity of the artery, by which it is demonstrated, that the pulse of the artery comes from the faculty pulsific, and that it is transmitted from the heart by the tunicles, and not by the impulsion of the blood within the Concavities; and therefore that the arteries are stretched as bellows, not as bags.  
This experiment is mentioned by Ves●alius, a man very skilful in Anatomy, but neither Galen nor Vesalius says, that they tried this experiment, which I did; only Vesalius prescribes it, and Galen counsels it to those that are desirous no find out the truth, not thinking, nor knowing the difficulty of that business, nor the vanity of it when it is done, since although it be performed with all manner of diligence, it makes nothing to the confirmation of that opinion, which affirms That the tunicles are the cause of pulsation, but rather shows That it is set awork by the impulsion of the blood. For so soon as above the reed or pipe you have with a band tied the artery, the artery above the ligature is presently dilated by the impulsion of the blood beyond the mouth of the pipe, from whence both the flux is stopped, and the impulsion reverberated, so that the artery under the band does beat with very little appearance, because the force of the passage of the blood does no way assist it, because it is returned above the ligature; but if the artery the cut off below the pipe, you shall see the contrary, from the leaping of the blood which is thrown out, and driven through the pipe, as in an aneurysm I have observed to come fró the exesion of the tunicles of the artery, this (whilst the blood is contained within the membranes) hath a contentive vessel of its flux praenaturally made, not of the dilated tunicles of the artery, but of the circumposition of the membrane and flesh. You shall see the inferior arteries beyond this aneurysm beat very weakly, whilst above, and especially in the aneurysm itself, the pulsations appear great and vehement, although we cannot there imagine, that the impulse or dilatation is made by the tunicles of the arteries, or by communication of the faculty of the Cyst; but merely by the impulsion of the blood.  
But that the error of Vesalius, and the small experience of others may the more clearly appear, who affirm (as they imagine) that the part under the pipe does not beat when the band is tied. I speak by experience, if you make the experiment rightly, that it will; and whereas they say, that upon the untying the band the arteries below xdo beat backwards, I say that the part below beats less when you have untied it, than when it is tied.  
But the effusion of blood which leaps out of the wound confuses all, and makes the experiment vain and to no purpose, so that there can be no certainty demonstrated, as I said, by reason of the blood. But if (and this I know by experience) you lay open the artery, and hold with your finger close that part which you cut, you may at your pleasure try many things which will evidently make the truth appear to you. First, you shall feel the blood, being forced, coming down into the artery, by which you shall see the artery dilated; as likewise you may squeeze out and let go the blood as you please: If you open a little part of the orifice and look narrowly to it, you shall see the blood at every pulse to be thrown out with a leaping, and as we said in the opening of an artery, or in the perforation of the heart, you shall see the blood to be thrown out in every contraction of the heart, in the dilatation of the artery.  
But if you suffer it to flow with a constant and continual flux, and give it leave to break out, either through the pipe, or by the open orifice, in the streaming of it both by your sight and by your touch you shall find all the strokes, order, vehemency, and intermission of the heart; just as you might feel in the pulse of your hand water squirted through a syringe at divers and several shootings, so you may perceive both by your sight and by its motion, the blood leaping out with a varying and unequal force. I have seen it sometimes in the cutting of the jugular artery break out with such force, that the blood being forced against the hand, did by its reverberation and refraction, fly back four or five foot.  
But that this doubt may be more clear, that the pulsific force does not flow through the Tunicles of the arteries from the hoant, I have a little piece of the artery descendant, together with two crural branches of it, about the length of a span, taken out of the body of a very worthy Gentleman, which turned to be a bone like a pipe, by the hollow of which, whilst this worthy Gentleman was alive, the blood in its descent to the feet did agitate the arteries by its impulsion; in which case nevertheless, although the artery were in the same condition as if it had been bound or tied above the little conduit-pipe, according to the experiment of Galen, that it could not either be dilalated in that place, nor straightened like a pair of bellows, nor from the heart derive its pulsific force, to the inferior and lesser arteries, nor yet carry through the solid substance of the bones that faculty which it had not received; yet I very well remember that I often observed whilst he was alive, that the pulse of the inferior artery did move in his legs and feet: wherefore it must needs follow, that in in that worthy Gentleman the inferior arteries were dilated by the impulsion of the blood, like bags, and not like bellows, by the stretching of the tunicles. For there must needs arrive the same inconvenience, and interception of the pulsific faculty, the tunicle of the artery being wholly converted into a conduit or pipe of bone, as might arrive from the reed or pipe which was tied, that the artery might not beat.  
I knew likewise in another worthy and gallant Gentleman, the aorta and a part of the great artery near the heart, turned into a round bone. So Galen's experiment, or at least one answerable to it, being not found out by industry, was found out by chance, and does manifestly evidence, that the interception of the pulsific faculty is not intercepted by the construction or ligature of the Tunicles, so that by that means the arteries cannot beat; and if the experiment which Galen prescribes, were rightly performed by any it would refute the opinion which Vesalius thought from thence to have confirmed. Yet for this cause do we not deny all motion to the tunicles of the arteries, but do attribute that to it which we grant to the heart, namely, that there is a coarctation and a Systole in the tunicles themselves, and from their distention a regress to their natural constitution. But if this is to be observed, that they are not dilated and straightened for the same cause, nor by the same instrument, but by several, as you may observe in the motion of all the parts, and in the heart; it is distended by the ear, contracted by itself, so the arteries are dilated by the heart, and fall of themselves.  
So you may make another experiment after the same manner. If you fill two saucers of the same measure, one of them with arterial blood which leaps out, the the other with venal blood, drawn out of a vein of the same Animal, you may presently by your sense, and afterwards too, when both the bloods are grown cold, observe what is the difference betwixt both the bloods, against those who do fancy another sort of blood in the arteries than is in the veins; namely they do ascribe to the veins a fresher sort of blood, I do not know which way boiling or blown up, swelling or bubbling, (like to honey or milk upon the fire) and so taking up more room.  
For if the blood which is driven out of the left ventricle into the arteries should be leavened, so as to be blown up, and foam after that manner, so that a drop or two should fill all the concavity of the aorta, no doubt it would when it fell again return to the quantity of some few drops (which cause some do allege for the emptiness of the arteries in dead men) and the same would be seen in the cotyla full of arterial blood; for so we find that it comes to pass in the cooling of milk or honey. But if in either cotyla the blood be found of the same colour, and congealed, of a not much different consistence, and squeezing out the whey after the same manner, and if it take up the same room both when it is hot and when it is cold, I think it will be a sufficient argument to gain any man's belief, and to confute the dreams of some, that there is neither in the left ventricle and sort of blood differing from that of the right, (as you may find out both by sense and reason) for you must needs likewise affirm. that the vena arteriosa should equally be distended with one drop of blood foaming up, and therefore that there is just such bubbling and leavened blood in the right as in the left, seeing the entry of the vena arteriosa, and the egress of the aorta, is equipollent and equal.  
Three things are chiefly ready to breed this opinion of the diversity of blood. One is, that in the cutting of an artery they see brighter blood drawn out; Another is, that in the dissection of dead bodies they find both the left ventricle of the heart and all the arteries so empty; A third is, that they imagine that the arterial blood is more spirituous, and more replete with Spirits; and therefore they think that it takes up more room: The cause and reason of all which things why they come to be so, by inspection is perceived.  
First, insomuch as concerns the colour, always and everywhere blood coming through a narrow hole, is as as it were strained and becomes thinner, and the lighter part of it, and which swims above, and is more penetrable, is thrust out: so in phlebotomy, the blood which springs out with great flux or force, and out of a greater orifice, and flies further, is always thicker, fuller, and darker coloured; but if it flow drops, (as it does out of a vein when the ligature is untied) it is brighter, for it is strained as it were, and only the thinner part comes out, as in the bleeding at nose, or that which is extracted by Leeches or Cupping-glasses, or any way issuing by diapedesin, is always seen more bright; because the thickness and hardness of the tunicles becomes more impassible, nor yields so pliably as to give an open way for the coming out of the blood: As it likewise happens in fat bodies, when by the fat under the skin the orifice of the vein is stopped, than the blood appears thinner, brighter, and as if it did flow from an artery. On the contrary, if you receive in a saucer the blood when you have cut an artery, if it flow freely, it shall appear like venal blood, there is blood much brighter in the lungs, and squeezed out from thence, than any is found in the arteries.  
The emptiness of the arteries in dead bodies (which did perchance cozen Erasistrasus, insomuch that he thought that the arteries contained only aerial spirits) proceeds from hence, because that when the lungs fall (their passages being stopped) the lungs do breath no longer, so that the blood cannot freely pass through them, yet the heart continues a while in its expulsion, whence both the left ventricle of the heart is more contracted, and the arteries likewise empty, and not filled by succession of blood, appear empty: But if the heart cease both at one time, and the lungs to give passage by respiration, as it is in those who are drowned in cold water, or in those who are taken suddenly with unexpected death, you shall find both the veins and the arteries full.  
As concerning the third, of the Spirits, what they are, and of what consistence, and how they are in the body, whether they be apart and distinct from the solid parts, or mixed with them, there are so many and so divers opinions, that it is no wonder if Spirits, whose nature is left so doubtful, do serve for a common escape to ignorance: For commonly ignorant persons when they cannot give a reason for any thing, they say presently that it is done by Spirits, and bring in Spirits as performers in all cases, and like as bad Poets, do bring in the gods upon the Scene by head and ears, to make the Exit and Catastrophe of their play.  
Fernelius and others do imagine aerial Spirits, and invisible substances; for he proves that there are animal Spirit (just as Erasistratus proves them in the arteries) because there are little cells in the brains which are empty, and since there is no vacuum, he concludes, that in living men they are full of Spirits.  
Yet all the School of Physicians agrees upon three sorts of Spirits, that the natural Spirits flow through the veins, the vital through the arteries, and the animal through the nerves, whence the Physicians say out of Galen, that the parts sometimes want the consent of the brain, because the faculty, together with its essence, is sometimes hindered, and sometime without the essence. Over and above besides these three sorts of influxive spirtis, they seem to assert so many more, which are implanted. But none of all these have we found by dissection, neither in the veins, nerves, arteries, nor parts of living persons. Some make corporeal Spirits, other some incorporeal Spirits; and those who make corporeal spirits sometimes say, that the blood or thinnest part of the blood is the conjunction of the soul with the body; sometimes they say, that the Spirits are contained in the blood (as flame in smoke) and sustained by the perpetual flux of it; sometimes they do distinguish them from the blood. Those that affirm that there are Spirits incorporeal know not how to tread, but likewise do affirm that there are potential Spirits, as Spirits concoctive, chilificative, procreative, and so many Spirits as there are faculties or parts.  
But the Schoolmen tell us also of a Spirit of Fortitude, Prudence, Patience, and of all the virtues, and the most holy Spirit of wisdom, and all divine gifts. They think too that bad and good Spirits do assist, possess, leave, and wander abroad. They think also, that diseases are caused by a Devil, as by a Cacochima. But although there is nothing more uncertain and doubtful, than the doctrine which is assigned to us concerning the spirit: yet for the most part all Physicians seem with Hippocrates to conclude, that our bodies are made up of three parts, containing, contained, and enforcing, by the forcing he means Spirits. But if Spirits must be understood to be every thing which enforces in a man's body, whatsoever hath the power or force of action in living bodies must be called by the name of Spirit Therefore all the Spirits are not aerial substances, nor powers, nor habits, nor incorporeal.  
But omitting the tediousness of all other significations to our purpose. Those Spirit which pass out through the veins or the arteries, are not separable from the blood, no more than flame form the flakes about it. But the blood and the Spirit signify the same thing, though divers in essence, as good Wine and its Spirit. For as Wine is no more Wine after it has lost its Spirit, but flat sluff or vinegar, so neither blood without Spirit is blood, but equivocally gore; as a hand of stone or a dead hand is no more a hand, so blood without vital spirit is no more to be esteemed blood. So the Spirit which is chiefly in the arteries, and the arterial blood is as its act, as the Spirit of Wine in Wine, and the Spirit of Aquavitae, or as a little flame kindled in the Spirit of Wine, and living by nouristing of itself.  
Therefore blood when it is most imbued with Spirits, it does require and look after more room, because it is swelled or leavened, and blown up by them (which you may certainly judge in my experiment which I brought concerning the measure of the saucers) but like wine, because it has greater strength and force of action and performance, in which it excels according to the mind of Hippocrates.  
Therefore the same blood is in the veins which is in the arteries, though it be acknowledged to be more full of Spirit, and more eminent in vital force: but it is not converted into something more aerial or vaporous, as if there were no Spirits but aerial ones, or none that had force but such as were flatuous and windy: But neither are the Animal Spirits, natural, and vital, which are contained in the solid parts, to wit, the ligaments and nerves (especially if there be so many several sorts of them) thought to be so many aerial forms, or divers sorts of vapours.  
Those who acknowledge Spirits in the bodies of creatures, but such as are corporal, but of an aerial consistence, or vaporous or fiery, of them would I fain know, Whether they can pass hither and thither, backward and forward as distinct bodies, without the blood? Whether or no I say, the Spirits follow the motion of the blood, as if they were either parts of the blood, or adhering to it by an indissoluble connexion, and an interrupted exhalation; so that they can neither leave the parts, nor pass without the influx, reflux, and passing of the blood.  
For if, as the vapours attenuated by the heat of the water, the Spirits, by the continual flux and succession of the blood, become the nourishment of the parts, it will necessarily follow, that they cannot remain apart from the nourishment, but do continually vanish, for that same reason that they neither flow back nor pass any way, nor abide, but according to the influxion, refluxion, or passing of the blood, as being either there subject, vehiculum, or nourishment.  
Then I would know, how they show us that Spirits are made in the heart, and do make them up, either by the compounding of exhalations, or vapours of the blood (Raised either by the heat or concussion of the heart.) Are not such Spirits to be thought much colder than the blood, since both the parts of which they are compounded, to wit, air, and vapour, are much colder? for the vapour of boiling water itself, and any flame burns less than the coal of a candle, and a wood-coal less than iron or brass red hot.  
whence it seems that such Spirits do owe their heat to the blood, rather than the blood is heated by the Spirits, and such Spirits are rather to be deemed fumes and excrements, flowing from the blood and body, (like smells) than workers in Nature; especially since they being so frail and vanishing, do so quickly lose that virtue, which in their original they receive from the blood.  
From whence it were likewise probable that there should be an expiration of the lungs, by which these Spirits being blown out might be ayr'd and purified, and that there should be an inspiration into them, that the blood passing through betwixt the two ventricles of the heart might be tempered by the ambient cold, lest being heated, and rising and swelling with a kind of fermentation, like boiling honey or milk, it should so distend the lungs as to suffocate the creature, as in a dangerous Asthma we have often seen: To which Galen likewise ascribes the reason, when he says, that this comes to pass by obstruction of the little arteries, namely the venous and arterious vessels. I have had experience of this, that by affixing of Cupping-glasses, and pouring upon them good store of cold water, there has many been saved, who have been in danger to be suffocated by an Asthma I have here, perchance, spoken sufficiently concerning Spirits, which we ought to define, and show what and how they are in a Treatise of physiology, only I will adjoin.  
Those that speak concerning innate warmth, as an ordinary instrument of Nature in performance of all things, and tell us of the necessity of influxive heat, to entertain all the parts, and keep them in life, and do acknowledge that it cannot exist without a subject, because they find a movable body disproportionable, by reason of the swiftness of the flux and reflux, (especially in the passions of the mind) and because of the swift motion of this heat, they introduce Spirits, as bodies most subtle, penetrative and movalbe, and just as they say, that from that ordinary instrument, to wit, the innate heat, proceeds the admirable divinity of Natural operations: so do they likewise affirm, that those Spirits of a sublime, bright, aethereal and celestial nature, are the bonds of the Soul; as the ignorant common-people when they do not conceive the reasons of things, think and say, that God in the immediate author of them. that is comes through the arteries; as if the blood could not be so speedily moved, not so full nourish; and in the confidence of this opinion they are so far advanced, that they deny that there is any blood contained in the arteries.  
Whence they resolve, that the influxive heat does come swiftly through all the parts, by the influx of Spirit, and And with very flight arguments they endeavour to ground this, that the arterial blood differs from the blood of the veins, or that the arteries are filled with such Spirits; and not with blood, contrary to all that which Galen both from reason and experience brought against Era●●stratus.  
But it is manifest by our former experiment, and by sense, that the arterial blood is not so different; the influx of the blood and spir't with it being not separate from the blood, but that it flows in one body through the arteries, sense may likewise make evident.  
You may observe when, and as often as the extremities of the hands, the feet, and the ears are stiff and cold, and are restored again by the influx of heat, that it happens that at the self-fame time they are coloured, warmed, and filled, and that the veins which were unseen before, do swell to plain appearance, from whence sometimes when they are suddenly warmed again the parts are sensible of some pain; from which it appears, that the same which by its influx brings heat, the same is it that fills and colours them, but this can be nothing else but blood, as was demonstrated before.  
Cutting off a long artery or vein anybody may see this evidently by sense, when he shall see the nearer part of the vein towards the heart let out no blood, but the further part pour it abundantly, and nothing but blood (as afterwards in my experiment which I set down, which I tried in the inner jugularie veins.) On the other side, cutting an artery, but a little blood flows from the further part, but the nearer part shoots with a violent force mere blood, as if it were out of a spout.  
By which experiment it is known which way the passage is in them, either this way or that way. Besides, you'll know what swiftness there is in it, what sensible motion, not by little and by drops, and with what violence to boot.  
But lest any would make an evasion, by pretending of invisible Spirits; Let the orifice of the vessel so dissected be let down into a vessel of water or oil, for if any herial thing came out, it would break out by visible bubbles; for after this manner Wasps, Hornets, and the like Insects, being drowned or suffocate in oil, send out at last bubbles from their tail when they are dying: from whence it is not improbable that they do take breath too whilst they are alive.  
For all creatures at last when they are drowned and stifled in the water, when they fail and sink, they use to send out bubbles out of their mouth and lungs, when they give up the glost.  
Lastly, it is assured by the same experiment, That the portals in the veins are so exactly shut, that air when it is blown in cannot pass, much less blood. I say it appears to the sense, that neither sensibly nor insensibly, neither by little, nor by drops, the blood is remoyed from the heart by the veins.  
And lest any should fly hither and say thus, That this comes to pass when Nature is troubled, and does act besides Nature, not when she is left to herself, and acts at her own freedom; seeing the same things appear in a sickly and preternatural constitution, which appear in good estate of body, it is not to be said, that cutting off a vein, since there flows so much blood from the further part, that this comes to pass beside Nature, because Nature is molested; for the dissection does not shut the further part, so that nothing can get out that way, nor can it be squeezed out whether Nature be troubled or no. Others do wrangle after the same manner, saying, That although when the artery is cut near the heart the blood breaks out in so great abundance immediately, yet for that cause the heart being whole, and the artery too, it does not always drive the blood by impulsion. Yet it is more likely, that all impulsion does drive something, nor can there be a pulse of the container without the impulsion of something contained: Yet some, that they might descend themselves, and decline the Circulation of the blood, are not afraid to affirm and maintain this; to wit, that the arteries in living creatures, and being according to Nature, are so full that they cannot receive a grain weight more of blood: and so likewise of the ventrieles of the heart. But it is without doubt, whensoever, or how much soever the arteries and ventricles are dilated, and contracted, they ought to receive greater impulsion of blood, and that beyond many grains. For if the ventricles be so distended as we have seen in the anatomy of living Creatures till they receive no more blood, the heart leaves beating, and continuing stiff and resisting, it occasions death by suffocation.  
Whether the blood be moved or driven, or move itself by its own intrinsical nature, we have spoken sufficiently in our book of the motion of the heart and blood; as also concerning the action, function, contraction, dilatation of the heart, how it is done, and together with the Dinstale of the arteries, so that those which take arguments from thence for contradiction, seem either not to understand what is said there, or else they will not try the business by their own sight.  
I believe there can not the attraction of any thing be demonstrated in the body but of the nutriment, which by succession of parts supplies by little & little that which is lost, as the oil of a lamp by the flame.  
Whence that is the first common organ of all sensible attraction & impulsion, which has the nature of a nerve, or of a fiber, or of a muscle, to wit, that it may be contracted, and that by shortening of itself it may stretch 〈◊〉 draw in, or thrust forward: but these things are more fully and openly to be declared elsewhere, in the organs of motion in living creatures.  
Insomuch as to those who do still reject the Circulation, because they neither see the efficient, nor final cause of it, There remains, because I have as yet joined nothing to it, only to say thus much; First you must confess that there is a Circulation, before you inquire for what it is, for from those things that do happen upon the circulation and allowance of it, the use and profits accrueing are to be searched. In the mean time I shall say so much, that there are many things allowed & received in physiology, pathology, and Medicine, that nobody knows the cause of, yet that there are such things nobody is ignorant, namely, of rotten fevers, revulsion, purgation of excrement, yet all these things are known by the help of Circulation.  
Whosoever therefore does oppose the Circulation of the blood, because so long as the Circulation stands, they cannot resolve physical Problems, or because in curing of diseases, and using of medicaments, they cannot from thence assign any cause of the symptoms, or see that those causes which from their Masters they have received, are false, or think it an unworthy thing to desert opinions approved heretofore, and think in unlawful to call in question the discipline which has been received through so many ages together with the authority of the ancients.  
To all these I answer, that the deeds of nature, which are manifest to the sense, care not for any opinion or any antiquity, for there is nothing more ancient than nature, or of greater authority.  
Besides, those problems out of medicinal observations not to be solved, as the Imagine, to the Circulation they object, and do oppose to it the declaring of their own errors, to wit, that if the circulation be true there can be no revulsion, since the blood is driven upon the part affected as before, and so it is to be feared, that there will be a passage of the excrements and blood, through the most noble and principal of our entrails. They do admire at the efflux and excretion, when out of the same body at divers holes, yea sometimes and the same hole, foul and corrupt blood issues, whereas if the blood were driven with a continual flux, pasing through the heat, it would be mixed and shaken together.  
They do doubt how these, and many other things that they fetch from the School of Physicians can come to pass, for they seem to be repugnant to the Circulation of the blood, nor do they think (as it is in astronomy) that it is enough to make new systems, unless you solve all scruples.  
I thought fit to return no other answer at this time, but that the Circulation is not the same everywhere, and at all times, but many things do happen from the swifter or slower motion of the blood, either through the strength or infirmity of the heat, which drives it, by the abundance, estate, or constitution of the blood, the thickness of the parts, obstruction, and the like; thicker blood hardly finds way through narrow passages; it is more strained when it passes the streyner of the liver, than when it passes the streyner of the lungs.  
It does not with a like speed pass through the thin contexture of the flesh, and parenchyme, as it does through the thick consistence of the nervous parts. For the thinner, more pure, and more spirituous part is sooner streynd through, the more earthy, cacochymick, and more tardy, stays longer, and is turned back. The nutritive part and last aliment (be it the Ros or Cambium) is more penetrative, seeing it is to be applied to every part, whether it be to the horns, feathers, or nails, if being everywhere nourished they increase in all their dimensions; for this reason the excrements in some places are voided, thickened, or do burden us, or are concocted: Nor do I think that there is any necessity that the excrements or ill humours, being once set apart, nor the milk, phlegm, nor sperm, or the last nutriment (the Ros and Cambium) should be returned with the blood, but that it behooves that that which nourishes should adhere, that it may be agglutinated. Of which, and a great many other things which are to be determined and declared in their proper places, to wit, in physiology, and the rest of the parts of physic, it is not fit to dispute, nor yet of the consequences of the Circulation of the blood, nor the conveniencies nor inconveniences of it, before the Circulation if self be established for granted.  
The example of astronomy is not here to be followed, where only from appearances, and such a thing that may be, the causes, and why such a thing should be, comes to be enquired after. But as one desiring to know the cause of the Eclipse, aught to be placed above the Moon, that by his sense he might find out the cause, not by reasoning of things sensible, in things which come under the notion of the sense, no surer demonstration can be to gain belief, than ocular testimony.  
I desire that there may be one other remarkable experiment tried by all that are desirous of the knowledge of the truth, by which likewise the pulse of the arteries is both seen to be done by the blood, and evidenced to be so.  
If the guts of a dog, or a wolf, or any Creature stuffed, and dried, such as you see at the Apothecaries, you cut away a part of it of any length., and fill it with water, and tie it at both ends that it is like a pudding, hitting or shaking the one end of it, in the end over against it, by putting too of your fingers (as we use to feel the pulse of the artery above the wrist) you may find every stroke and difference of the motion clearly. And after this manner in every swelling vein either of living or dead, you may to raw students manifest all the diferences of the pulses to the sense, in greatness, frequency, vehemency, and rhyme. For as it is in a long bladder or in a long drum, all the strokes of one of the extremes is felt likewise in the other; Therefore in the hydropsy of the belly, as likewise in all abscessions which are filled with liquid matter, we use to distinguish an Anasarca from a Tympanitis; If all pulses and vibrations made in one side be by touch clearly felt in the other, we think it a Tympanitis, and not as it is falsely believed, because it is like the sound of a drum, and is only by flatuousness, but because (as it is in a drum) every light stroke passes through it, and every shake goes through the whole; for it shows that there is a serous an wheyish substance within, and not a tough and slimy, as in the Anasarca, which being thrust retains the marks of the stroke or impulsion, and transmits it not. Having opened this experiment, there rises a most powerful objection against the Circulation of the blood, neither observed, nor opposed against me by any that has hitherto written. Seeing in this experiment we see that there may be Systoles etc Diastoles, without the egress of the liquour, who will believe but that it may be just so in the arteries, and that in them just so as it is in an Euripus, from hence thither, from thence hither, it may be driven by turns. But in another place we have sufficiently resolved this doubt, and now we also say, that this is not so in the arteries of living creatures, because continually and incessantly the right ear of the heart fills the ventricles with blood, the return of which the three-pointed portals hinder, and so the lefs ear fills the left ventricle, and both the ventricles in the Systole throw forth the blood which the Sigmoidal portals hinder to return, and that it ought therefore either pass some way, and continually out of the lungs and arteries, or otherwise it would at last by restagnation and intrusion, break the vessels which contain it, or suffocate the heart itself by distention, as we have observed to be plain to the sense in the dissection of a live Adder, in my Book concerning the motion of the blood.  
To clear this doubt I will recite to you two experiments amongst many other (of which I cold one before) by which it clearly appears, that the blood in the veins, with a continual and great flux runs continually towards the hearts  
In the internal jugular vein of a live do, which I laid open before a great part of the Nobility, and the King my Royal Master standing by, which was cut and broke off in the middle: From the lower part rising from the Gl●vicule, scarce a few drops did issue; whilst in the mean time the blood with great force, and breaking out of a round stream, ran out most plentifully downwards from the head through the other orifice of the vein. You may observe the same daily in phlebotomy in the flowing out of the blood, if you hold the vein fast with one finger a little below the orifice, presently the flux is stopped, which after you let it go flows abundantly, as before.  
In any visible long vein of your arm, stretching out your hand, and pressing out all the blood downwards as much as you can, you shall see the vein fall, leaving as it were a sorrow in the place, but so soon as you thrust it back with one of your fingers, you shall presently see the part towards the hand to be filled, and swell, and to rise by the return of the blood from the hand. What is the reason, that by stopping of the breath, and by that means streightning the lungs, and a great deal of it being within, the pectoral vessels are straightened, whence the blood is driven into the face, and eyes, with so much redness?  
Nay that (as Aristotle says in his problems) all actions are performed with greater strength by keeping in of the breath, than by letting it free? so you get blood more abundantly out of the veins the brow, or tongue, by compression of the throat, and retention of breath.  
I have found sometimes in a man's body, newly hanged, 2 hours after his execution, before the redness of his face was gone, opening up his heart, and Pericardium, the right ear of his heart, and lungs much stuffed, and distended with blood, many witnesses standing by, especially I showed them the ear, as big as a man's fist, so swelled, that you would have thought it would have burst with greatness, which, the body being afterwards cold, and the blood having found other ways, was quite gone.  
So from these, and other experiments, it is clear enough, that the blood runs through all the veins to the basis of the heart, and that unless it found passage it behoved to be straightened, or shut up in other ways, and that the heart would be overwhelmed with it, as on the other part, if it did not flow out of the arteries, but were regurgitated, the oppression by it would quickly appear.  
I will add another observation: A noble Knight Baronet Sir Robert Darcie father to the Son-in-Law of the most learned man, and my very great friend, and a famous physician, Dr. Argent, about the middle of his age, did often complain of an oppressive pain in his breast, especially in the night time, so that sometimes being afraid of collapsion of spirits, sometimes fearing suffocation by a paroxysm, he led an unquiet and anxious life, using the counsel of all Physicians, and taking many things in vain, at last the disease prevailing, he becomes cachectick, and hydropic, and at last oppressed in a signal paroxysm he died, In his corpse, in the presence of Dr. Argent, who at that time was President of the College of Physicians, and Dr. Gorge, a rare Divine, and a good Preacher, who was at that time Minister of that Parish, by the hindrance of the passage of the blood out of the left ventricle into the arteries, the wall of the left ventricle itself (which is seen to be thick and strong enough) was broken, and poured forth blood at a wide hole, for it was a hole so big, that it would easily receive one of my fingers.  
I knew another stout man, who did so boil with rage because he had suffered an injury, and received an affront by one that was more powerful than himself, that his anger and hatred being increased every day (by reason he could not be revenged) and discovering the passion of his mind to nobody, which was so exulcerate within him, at last he fell into a strange sort of a disease, and was torured, and miserably tormented with great oppression and pain in his heart, and breast, so that the most skilful Physicians prescriptions doing no good upon him, at last, after some years, he fell sick of the scorbutic disease, pined away, and died.  
This man only found ease as oft as his breast was pressed down by a strong man, and was thumped and beaten down as they do when they mould bread: his friends thought he was bewitched, or possessed with the Devil.  
He likewise had his jugular arteries distended about the greatness of ones thumbs, as if either of them had been the Aorta itself, or the Arteria magna in its descent, and did beat vehemently, and were to the view like two long Aneurisms, which caused us try blood-letting in his temples, but that gave him no ease. In his corpse I found the heart and the aorta so distended and full of blood, that the bigness of his heart, and the concavities of the ventricles, were equal in bigness to that of an ox; so great is the strength of the blood when it is shut up, and so vast its force.  
Although then (by the experiment newly mentioned) there may be animpulsion without an exite (inthe shaking of water up and down) in the pudding aforementioned, yet cannot it be so in the blood which is in the vessels of living persons, without very great and heavy impediments and dangers.  
Yet from thence it is manifest, that the blood in its Circulation does not pass every There with the same agility and swiftness, nor with the same vehemence in all places and parts, and at all times, but that it varies much according to the age, sex, temper, habir of body, and other contingents, external internal, natural, or preternatural.  
For it does not pass through the crooked and obstructed passages, with the same swiftness as it does through those that are open, free, and patent; nor does it pass through bodies or dense parts, and such as are stuffed or constricted, as it does through those that are thin, open, and without obstruction; nor does it run out so swiftly and penetratively when the impulsion is slow and soft, as when it is drive with force and strength, and thrust forward with vehemency and abundance. Nor is the thick blood or solid mass, or when it is made earthy, so penetrative, as when it is more wheyish, made thin, and liquid.  
And therefore with reason we may imagine, that the blood in its Circulation goes flowlier through the reins, than through the substance of the heart; swiftlier through the liver, than through the reins; swiftlier through the spleen, than through the liver; swiftlier through the lungs, than through the flesh, or any other viscers of thinner contexture.  
We may likewise contemplate in the age, sex, temperature, habit of the body soft or hard, of the ambient cold, which condenses bodies, when the veins scarce appear in the members, or the sanguine colour is seen, or the heat appears, the blood being made more liquid by reception of nutriment. So like wise the veins do more conspicuously, and freely pour out the blood the body being heated before opening of a vein than when it is cold. We see that the passion of the mind (in the administration of phlebotomy) if any fearful person chance to sound, straight the flux of the blood is stopped, and a bloodless paleness seizes on all the superfice of his body, his members are stiff, his ears sing, his eyes grow dim, and are in convulsion. I find here a field where I might run our further, and exspatiate at large in speculation: But from hence so great a light of truth appears, from which so many questions may be resolved, so many doubts answered, so many causes and cures of diseases found out, that they seem to require a particular treatise. Concerning all which in my medicinal observations, I'll set down things worthy your admiration.  
For what is more admirable, than that in all affections, desires, hope, or fear, our bodies suffer several ways, our very countenances are changed, and our blood is seen to fly up and down? with anger our eyes are red, the black of the eye is lessened in shamefastness, and the cheeks are flushed with redness; by fear, infamy, and shame, the face is pale, the ears glow, as if they should hear soon ill thing: young men that are touched with lust, how quickly is their nerve filled with blood, erected and extended? But it is most worthy the observation of Physicians, why blood-letting and cupping glasses, and the stopping of the artery which carries the flux (especially whilst they are doing) does as it were with a charm take away all pain and grief: I say, such things as these are to be referred to observations, where they are explained clearly.  
Frivolous and unexperienced persons do scurvily strive to overthrow by logical, and far-fetched arguments, or to establish such things as are merely to be confirmed a by anatomical dissection, and ocular testimony. It behooves him, who ever is desirous to learn, to see any thing which is in question, if it be obvious to sense, and sight, whether it be so or no, or else be bound to believe those that have made trial, for by no other clearer or more evident certainty can he learn or be taught. Who will persuade a man that has not tasted them, that sweet or new wine is better than water? with what arguments shall one persuade a blind man that the Sun is clear, and outshines all the Stars in the firmament? So concerning the Circulation of the blood, which all have had confirmed to them for so many years, by so many ocular experiments, there has been hitherto no man found, who by his observations could refute a thing so obvious to the sense (to wit the motion of flux and reflux) by observations alike obvious to the sense, or destroy the confirmed experience of it, nay by ocular testimony none ever offered to build up a contrary opinion.  
Whilst in the mean time there are not wanting person, who for their unskilfulness, and little experience in anatomy, having nothing agreeable to sense to oppose to it, they cavil at it with some vain assertions, and such as they adhere to from the authority of Teachers, with no solid supposition, but with idle and frivolous arguments, and bark at it besides with a great many other words, and those base ones too, with railing, and base scurvy language, by which they do no more than show their own vanity, and folly, and their baseness, and want of arguments, which are to be fetched from sense, so that they with their false sophistical arguments do rage against sense: just as when the raging winds advancing the waves in the Sicilian Sea dashes them in pieces against the rocks within Charybdis, they make a hideous noise, and being broken and reverberated hiss, and foam, so do these men rage against the reason of their own sense.  
If nothing should be admitted by sense without the testimony of reason, or sometimes against the dictate of reason, there should be no question now to be controverted.  
If our most certain Authors were not our senses, and these things were to be established by reasoning, as the Geometricians do in their frames, we should truly admit of no Science, for it is the rational demonstration of geometry from things sensible to demonstrate things to the sense, according to which example, things abstruse, and hid from the sense, grow more manifest by things which are easier, and better known, Aristotle advises us much better lib. 31 de Gen. Anim, disputing of the generation of Bees, says he, you must give credit to your senses; if those things which are demonstrated to you are agreeable to those things which are perciptible by sense, which, as they shall then be better known, so you may better trust your sense than your reason. Whence we ought to approve or reject all things by examination leisurely made, but if you will examine or try whether they be said right or wrong, you must bring them to the test of sense, and confirm, and establish them by the judgement of sense, where, if there be any thing feigned or not, sure it will appear. Whence Plato says in his Critias, That the explication of those things is not hard, of which we can come to the experiment, nor are those auditors fit for Science, that have no experience.  
How hard and difficult a thing is it for those that have no experience, to teach such things of which they have no experience, or sensible knowledge; and how unfit and indocile unexperienced Auditors are to true Science, the judgement of blinde-men in colours, and of deaf men in the distinctió of sounds, does plainly show. Who shall ever teach the flux and reflux of the Sea? or by a Geometrical Diagram teach the quantities of Angles, or the computation of the sides of a figure to a blindman, or to those that never saw the Sea, nor a Diagram? A man that is not expert in anatomy, in so far as he cannot conceive the business with his own eyes, and proper reach, in so far is thought to be blind to learning, and unfit: for he knows not truly any thing concerning which an Anatomist disputes, nor any thing, from the implanted nature of which he should take his argument, but all things he is alike ignorant of, as well those things which are gathered and concluded, as the things from whence. But there is no possible knowledge, which arrives not from a pre-existent knowledge, and that very demonstrable. This one cause is the chief reason why the knowledge we have of the heavenly bodies is so uncertain and conjectural. Very fain would I know from those ignorant persons, that profess the causes and reasons of all things, why as both the eyes in beholding move together every way, nor particularly one moves this way, and the other that way, so neither both the ears of the heart?  
Because they know not the causes of fevers, or of the plague, or the admirable properties of some medicaments, and the causes why they are so, must therefore these things be denied?  
Why is the Birth that breathes not till the tenth month, not suffocated for want of air? since one that is born in the seventh or eighth, so soon as he has breathed in the air, is presently choked if it have no air? How can it retain life whilst it is yet within the Secundine, or as yet not come forth, without breath? but so soon as hecomes into the air unless he breathe he cannot live?  
Because I see many men doubtful in the Circulation, and some men oppose such things which understand them not aright, as I intended them, I shall bridfly rehearse out of my Book of the motion of the heart and blood, what I did there intend. The blood which is contained in the veins (as in its own hold) where it is most abundant (to wit, in the vena cava) near to the Bajis of the heart, and the right ear, growing hot by little and little by its own internal heat, and made thin, it swells and rises (like leaven) whence the ear being first dilated, and afterwards contracting itself by its pulsific faculty, streightways drives it out into the right ventricle of the heart, which being filled in its Systole, and consequently freeing itself from that blood which is driven into it (the three-pointed portals refusing passage to it) it drives the same blood into the vena arteriosa (where the passage is open) by which it does distend it. Now the blood in the arterious vessel being not able to return against the Sigmoidal portals, but because the lungs are extended, amplified, and restricted both by imspiration and expiration, and likewise their vessels, they give passage to this blood into the arteria venosa: of which the left ear keeping together equal motion, time and order, with the right ear, and performing its function, sends the same blood into the left ventricle, as the right trickle sent into the right, whence the left ventricle together, and at the same time with the right (since it can gain no regress, by reason of the portals which hinder its return) drives it into the capaciousness of the aorta, and consequently into all the branches of the artery; the arteries being filled with this sudden pulse, being not able so suddenly to disburden themselves, are distended, suffer an impulsion and Diastole.  
Whence I gather, seeing the same is reiterated continually and incessantly, that the arteries, both in the lungs, and in the whole body, by so many strokes, and impulsions of the heart, would be so distended and stuffed with blood, at least that either the impulsion would give over all together, or else the arteries would burst, or be so dilated, that would contain the whole mass of blood which is in the veins, unless the efflux of blood were disburdened somewhere.  
We may likewise reason after the same manner of the ventricles of the heart, being filled & stuffed with blood, unless the arteries did likewise disburden, they would be at last distended and destitute of all motion. This consequence of mine is demonstrative and true, and follows of necessity, if the premises be true; but our senses ought of assure us whether such things be false or true, and not our reason, ocular testimony, and no contemtplation.  
I affirm likewise of the blood in the veins, that the blood does always, and everywhere, run out of the less into the greater, and hastens towards the heart from every part: whence I gather, that whatsoever quantity which is continually sent in, the arteries do receive by the veins, that the same does return and does at last flow back thither from whence it is first driven, and that by this means the blood moves circularly, being driven in its flux and reflux by the heart, by whose force it is driven into all the fibers of the arteries, and that it does afterwards successively, by a continual flux return through the veins, from all those parts which draw, and streyn it through; sense itself teaches us that this is true, and collections from things obvious to sense takes away all occasion of doubt.  
Lastly, this is that I did endeavour to relate and lay open by my observations and experiments, and not to demonstrate by causes and probable principles, but to confirm it by sense and experience, as by a powerful authority, according to the rule of Anatomists.  
From these we may observe what force, and violence, and strong vehemency we perceive in the heart, and greater arteries by touch & sight. I do not say, that in all the vessels which contain the blood, the pulse of the Systole and Diastole is the same (in greater Creatures) nor in all creatures which have blood, but that there is such a one and so great in all, that by that means there is a flux of blood, and swifter course of it through the small arteries, the porosities of the parts and branches of all the veins, and from thence comes the Circulation: for neither the small arteries, nor the veins do beat, but only the arteries which are nighest to the heart, because they do not so soon send the blood out, as it is driven into them, for you may try, opening of an artery, if the blood leap out in full stream, so that it come out as freely as it went in, that you scarce found any pulse in that artery through which it passes, because the blood running through, and finding passage, does not distend it. In Fishes, Serpents, and colder creatures, the heart beats slowly and weaker, that you will hardly perceive any pulse in the arteries, because they pass their blood through very slowly; whence it is that in these as also in the little fibers of the arteries of a man there is no distinction by blood; because they are not pierced with impulsion of blood.  
As I said before, the blood that passes through an artery which is cut and opened, makes no pulse there at all, whence it clearly appears, that the arteries suffer their Diastole neither by innate pulsific faculty, nor by any granted them from the heart, but by the mere impulsion of the blood. For in the full flux, flowing out the length of its course, you may by touch perceive both the Systole and Diastole, as I said before, and all the differences of the pulse of the heart, their time, order, vehemency, intermission in the emanation of th' eflux evidently, (as it were in a looking-glass.) Just as water, by the force and impulsion of a spout is driven aloft through pipes of lead, we may observe and distinguish all the forcings of the Engine, though you be a good way off, in the flux of the water when it passes out, the order, beginning increase, end, and vehemency of every motion. Even so it is when you cut off the orifice of an artery; where you must observe, That as in the water, the flux is continual; though it be sometimes nigher, sometimes further: so in the arteries, besides the shaking, pulse, and concussion of the blood, (which is not equally to be perceived in all) from that time forward there is a continual motion and fluxion in the blood, till the blood be again returned to that place where it first began, that is to say, to the right ear.  
These things you may try at your pleasure cutting up one of the longer arteries, (as the jugular) which if you take betwixt your fingers, you shall clearly discern how it loses its pulse and recovers it again, beats less or more. And as these things may be tried whilst the breast is whole; so opening the breast, and the lungs afterwards being collapsed, and all motion of respiration gone, you may easily try it, to wit, that the left ear is contracted and emptied, that it becomes more whitish, and that it doth at last, together with the left ventricle, intermit in its pulse, beat leisurely, and at last leave off: And likewise by the hole which you may cut in the artery, you may see the blood come forth less and less in a smaller thread, and that at last, (to wit, in the defect of blood, and the impulsion of the left ventricle) no more will flow.  
You may likewise try this same in the tying of the vena arteriosa, and so take away the pulse of the left ear, and with untying it, restore the pulse at your pleasure. Whence the same thing is evidently tried by experiment, which is seen in dying persons, that as first the left ventricle desists from motion and pulse, and afterwards the left ear, than the right ventricle, & pulse, lastly, the right ear; so where the vital faculty begins first, it ends last.  
Which being tried by the sense, it is manifest, that the blood passes only through the semptum of the heart, and not through the lungs, and only through them whilst they are moved in respiration, and not when they are fallen or disquieted. For which cause in an Embryon (not as yet breathing) Nature instead of the passage in the arteria venosa, (that matter may be furnished to the left ventricle, and the left ear) opens an oval hole, which she shuts in young men, and those that breath freely.  
It likewise appears, why those that have the vessels of their lungs oppressed, and stuffed, or those that have any loss of their breath, it is present token of death.  
It is likewise clear, why the blood of the lungs is so flame-coloured; for it is thinnest that is strained through there. It is beside to be observed from our former conclusion, in order to those who require the causes of Circulation, & think the power of the heart to be the effecter of all things, and as it is the author of transmission by pulse, so with Aristotle they think it the author of attraction, and generation of blood, and that the Spirits are made by the heart, and the influxive heat (& that by the innat heat of the heart, as by the immediate instrument of the soul, or by a common bond and the first organ for perfecting of all the works of life. And so the motion of the blood and spirit, its perfection and heat, and every property thereof, to be borrowed from the heart, as from its beginning; (which Arist. says is in in the blood, as in hot water, or boiling pottage) is in the heart, and that it is the first cause of pulsation and life. If I may speak freely. I do not think that these things are so (as they are commonly believed) for there are many things which persuade me to that opinion, which I will take notice of in the generation of creatures, which are not fit here to be rehearsed; but it may be things more wonderful than these, and such as will give more light to natural philosophy, shall be published by me.  
Yet in the mean time I will say and propound it without demonstration, (with the leave of most learned men, and reverence to antiquity) that the heart, as it is the beginning of all things in the body, the spring, fountain, and first causer of life, is so to be taken, as being joined, together with the veins, and all arteries, and the blood which is contained in them. Like as the brain, (together with all its sensible nerves, organs, and spinal marrow) is the adequate organ of the sense, (as the phrase is.) But if you understand by this word heart, the body of the heart, with the ventricles and ears, I do not think it to be the framer of the blood, and that it has not force, virtue, motion, or heat, as the gift of the heart; and next, that the same is not the cause of the Diastole & distention which is the cause of the Systole and contraction, whether in the ears or arteries: but that part of the pulse which is called a Diastole comes of another cause, diverse from the Systole, and aught to go before every Systole. I think the first cause of distention is innate heat in the blood itself, which (like leaven) by little and little attenuated and swelling, is the last thing that is extinct in the creature. I agree to Aristotle's instance of pottage, or milk, in so far as he thinks that elevation or depression of the blood does not come of vapours or exhalations, or Spirits raised into a vaporous or eareal form, nor is not caused by any external agent, but by the regulating of Nature, an internal principle.  
Nor is the heart (as some think) like a charcoal-fire (like a hot Kettle) the beginning of heat and blood, but rather the blood delivers that heat which it has received to the heart, as likewise to all the rest of the parts, as being the hottest of all. Therefore arteries, and the coronal veins are assigned to the heart for that use which they are assigned to the rest of the parts, to wit, for influx of heat for the entertaining and conservation of it, therefore all the hotter parts, how much more sanguine they are, and more abundant with blood, they are said convertibly so to be, and thus the heart having signal concavities, is to be thought the warehouse, continual fire, and fountain of the blood, not because of the corpulency of it but because of the blood which it contains like a hot Kettle, as in the same manner the spleen, lungs, an other parts are thought hot, because they have many veins or vessels containing blood.  
And after this manner do I believe that the native heat, called innate, to be the first efficient cause of pulse, as likewise to be the common instrument of all operations. This as yet I do not constantly aver, but propound it as a Thesis; I would fain know what may be objected by good and learned men, without scurrility of words, reproaches, or base language, and anybody shall be welcome to do it.  
These things than are as it were the parts and the footsteps of the passage, and Circulation of the blood; to wit, from the right ear into the ventricle, out of the ventricle through the lungs into the left ear, then into the left ventricle, into the aorta, and into all the arteries from the heart, by the porosities of the part into the veins, and by the veins into the Basis of the heart, the blood returns most spedity.  
By an experiment any man may try that pleases by the veins, let the arm be tied as the custom is with a gentle ligature, and let it remain tied so long, still moving the arm up and down, till the veins all of them swell exceedingly, and the skin grow very red below the ligature, and then let the hand be washed with Snow or cold water, till the blood gathered below the ligature be cold enough, then presently untying the ligature, you [shall find by the cold blood which returns how swiftly it runs back to the heart, and what a change it will make in its return] thither, so that it is not to be wondered at, that in the untying of the ligature in blood letting some have sounded. This experiment does demonstrate that the veins below the ligature do not swell with blood attenuated, and puffed up with spirit, but with blood only, and such blood which can be reverberated into the arteries through the Anastomosis of the parts, or the hidden Meanders.  
It likewise shows how those that pass over snowy mountains, are often suddenly seized with death, and many such like.  
Lest it should seem a difficult business, how the blood should pass through the pores of the parts, and go hither and thither. I will add one experiment. It happens after the same manner to those that are strangled, and hanged with a rope, as it does in the typing of the arm that beyond the cord their face, eyes, lips, tongue, and all the upper parts of their head are stusted, with very much blood grow extreamred, and swell till they look black, in such a carcase untying the rope, in whatsoever position you set it, within a very few hours you shall see all the blood leave the face and the head, and see it as it were fall down with its own weight, from the upper to the lower parts through the pores of the skin and flesh, and the rest of the parts, and that it fills all the parts below and the skin chiefly, & colours it with black matter; how much more lively and sprightly the blood is in a living body, and by how much more penetrating it is through the porosites than congealed blood,, especially when it is condensed through all the habit of the body, by the cold of death, the ways too being stopped and hindered, so much the more easy and ready is the passage in those that are alive through all the parts.  
Renatus de Cartes a most acute and ingenious man (to whom for his honourable mentioning of my name I am much indebted) and others with him, when they see the heart of a fish taken out placed upon an even board imitate a pulse (by collecting itself) in its erection, up-lifting, vigoration, they think that it is ampliated, and dilated, and that the ventricles of it become more capacious, not according to my opinion. For when it is gathered, at that time, the capacities of it are rather straightened, and it is certain that it is then in its Sistole, and not in its Diastole, as neither when it falls weak and flagging, and is relaxed, it is then in its Diastole, or distention, and thence the ventricles become wider; so in a dead man we do not say that his heart is in the Diastole; because it is flagging without any Systole, destitute of all manner of motion, and not distended at all, for it is distended properly, and is in the Diastole when it is filled by the impulsion of the blood, and contraction of the ear, as in the anatomy of living things is evident enough.  
Therefore they understand not how much the relaxation, and falling of the heart and arteries differ from their distention and Diastole; that distention, relaxation, and constriction, come not of the same causes, but from contrary causes, as making contrary effects; and diverse, as making divers motions, as all Anatomists know very well, that the opposite muscles in any part (called Antagonistae) are the causes of several motions, to wit, of adduction, and extension, so there is necessarily by nature framed contrary, and divers active organs, for contrary and divers motions.  
Nor does this efficient cause of pulse which he sets down according to Aristotle please me, to wit, that the ebullition of the blood shall be both the cause of the Systole, and of the Diastole. For these motions are sudden strokes, and swift hits. And there is nothing that swells so like leaven, or boils up so suddenly in the twinkling of an eye, and falls again, but that rises leisurely, and falls suddenly; besides, indissection you may by your own eyesight discern, that the ventricles of the heart are distended, and filled by the constriction of the ears, and are increased in bigness according as they are filled, more or less, and that the distention of the heart is a kind of violent motion, done by impulsion, not by an attraction.  
There are some who think, as there is no need of impulsion for the aliment in the nourishing of Plants, but it is by little and little drawn into the place of that which is spent by the indigent parts; so the vegetive faculty performs its work alike in both, but there is a difference. Calid influxive is continually required to the entertaining of the members of creatures, and preserving of vivifying heat in them, and for restoring of the parts which suffer by outward injury, and not for nutrition only.  
So much of Circulation, which if it be not duly performed, or be hindered or perverted, or go too swiftly, there follows many dangerous sorts of diseases, and admirable symptoms, either in the veins, as swellings, abscessions, griefs, haemeroids, flux of blood, or in the arteries, as swellings, boils, strong and pricking pains, aneurisms, tumours in the flesh, fluxions, sudden suffocations, asthmas, stupidity, apoplexy, and others innumerable. Likewise it is not fit to tell in this place, how as it were with an Enchantment, many things are cured, and taken away, which were thought incurable.  
I may set down such things in my medicinal observations, and discourses of pathology, which I have hitherto known to be observed by none.  
I will conclude (most learned Riolax) to give you more ample satisfaction, because you think that there is no Circulation in the mesentericks; Let the vena porta be tied near to the cymus of the liver in a live dissection, which you may easily try, you shall see by the swelling of the veins beneath the ligature, that same come to pass which happens in blood-letting by tying of the arm, which will show you the passage of the blood there.  
And when you shall hear any man of that opinion, that by Anastomosis the blood can come out of the veins into the arteries, tie in a live dissection the great vein, near the division of the crurals, and as soon as you cut the artery (because it finds passage) you shall see all the mass of blood emptied out of all the veins (nay out of the ascendent cava too) by the pulse of the heart, in a very short time, yet that below the ligature the crural veins & parts below are only full. Which, if it could any way have returned into the arteries by an Anastomosis, should never have come to pass.   
FINIS.