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Harvey’s great work, though by no means the largest in bulk, is the one on the Motions of the Heart and Blood. It has been said, happily, by a recent critical writer, that “men were already practising what Bacon came to inculcate,” viz. induction upon data carefully collected and considered; and it would not be easy to adduce a more striking example of the way in which ultimate rational truth is arrived at by a succession of inferences than is contained in Harvey’s Essay on the Heart and Blood. Had Bacon written his Novum Organum from Harvey’s work as a text, he would scarcely have expressed himself otherwise than as he has done, or given different rules for philosophizing than those which he has laid down in his celebrated treatise.[28]

In his introduction, and by way of clearing the ground, Harvey exposes the views of preceding physiologists, ancient and modern, in regard to the motions of the heart, lungs, and blood, to the state of the arteries, &c.—in short, he gives the accredited physiology of the thoracic viscera, with comments, which prove it a mass of unintelligible and irreconcilable confusion. There is room, therefore, for another interpretation, consonant with reason and with anatomical fact, and susceptible of demonstration by the senses. When he first essayed himself to comprehend the motions of the heart, and to make out the uses of the organ from the dissection of living animals, he found the subject so beset with difficulties that he was almost inclined at one time to say with Fracastorius, that these motions and their purpose could be comprehended by God alone. By degrees, however, by repeating his observations, using greater care, and giving more concentrated attention, he at last discovers a way out of the labyrinth, and a means of explaining simply all that had previously appeared so obscure. Hence the occasion of his writing. Such is the burthen of the proem and first chapter. With Harvey’s admirable work now put in an accessible shape into his hands, we should (did we proceed with an analysis) but anticipate the intelligent reader in the great pleasure he will have in following the author through the different steps of his argument until the conclusion is reached, and the inference presents itself as inevitable, namely, that the blood must circle round and round in one determinate course, in the body as in the lungs, incessantly. For Harvey, it must be here observed, left the doctrine of the circulation as an inference or induction only, not as a sensible demonstration. He adduced certain circumstances, and quoted various anatomical facts which made a continuous transit of the blood from the arteries into the veins, from the veins into the arteries, a necessary consequence; but he never saw this transit; his idea of the way in which it was accomplished was even defective; he had no notion of the one order of sanguiferous vessels ending by uninterrupted continuity, or by an intermediate vascular network, in the other order. This was the demonstration of a later day, and of one who first saw the light in the course of the very year when Harvey’s work on the Heart was published.[29]

The appearance of Harvey’s book on the Motion of the Heart and Blood seems almost immediately to have attracted the attention of all the better intellects among the medical men of Europe. The subject was not one, indeed, greatly calculated to interest the mass of mere practitioners; had it been a book of receipts it would have had a better chance with them; but the anatomists and physiologists and scientific physicians would seem at once to have taken it up and canvassed its merits. The conclusions come to in the work, there can be no question, took the medical world by surprise; it was not prepared for such a proposition as a ceaseless circular movement of the blood, with the heart for the propelling organ; for the latter point, be it understood, was even as great a novelty as the former.

Coming unexpectedly, and differing so widely from the ancient and accepted notions, we cannot wonder that Harvey’s views were at first rejected almost universally. The older intellects, in possession of the seats and places of authority, regarded them as idle dreams; and upon the faith of this conclusion, their author was set down and treated by the vulgar as a crackbrained innovator. Two years, however, elapsed before aught in contravention of the new doctrines saw the light, and this came at length not from any of the more mature anatomists of Europe—their minds were made up, the thing was absurd—but from a young physician, of the name of Primerose, of Scottish descent, but French by birth. Primerose had been a pupil of Joannes Riolanus, professor of anatomy in the University of Paris; he had doubtless listened to his master’s demonstration of the absurdity of the Harveian doctrine of the circulation, and by and by he set himself down, by way apparently of exercising his ingenuity, to try the question, not by fact and experiment, but by the precepts he had imbibed from his teacher and the texts of the ancients. The essay of Primerose[30] may be regarded as a defence of the physiological ideas of Galen against the innovations of Harvey. It is remarkable for any characteristic rather than that of a candid spirit in pursuit of truth; it abounds in obstinate denials, and sometimes in what may be termed dishonest perversions of simple matters of fact, and in its whole course appeals not once to experiment as a means of investigation.—Harvey, having already, and in the very outset of his work, demonstrated the notions untenable which it was Primerose’s purpose to reassert and defend, of course deigned him no reply; he could never dream of going over the barren ground he had already trodden, in the hope of convincing such an antagonist.

Æmylius Parisanus, a physician of Venice, was the next to assail the Harveian doctrine of the circulation,[31] and still with the old instruments—the authority of Galen and the ancients generally. Parisanus perceived Harvey’s views as directly contravening an hypothesis to which he had formerly committed himself, namely, that the spleen was the organ of sanguification and the furnisher of nutriment to the heart; on this ground may Parisanus have been led to enter the lists against the new opinions. But he proved a most flimsy antagonist. Ignorant of some of the commonest points of anatomy, and frequently misinterpreting the writer he combats, writing himself in a style the most elaborately involved, and consequently obscure, it is frequently difficult even to guess at his meaning. Like his countryman of the poet, Signor Gratiano, he

“Speaks an infinite deal of nothing; more than any man in all Venice: his reasons are two grains of wheat hid in two bushels of chaff; you shall seek all day ere you find them; and when you have them they are not worth the search.”

Had not Dr. Ent, in his Apology for the Circulation, given the name a place on his title-page, Parisanus’s opposition would scarcely have merited mention here.

Nearly at the same time with Parisanus, Caspar Hofmann, the learned and laborious professor of Nuremberg, attracted particular attention, both in his teaching and his writings, as the opponent of the Harveian doctrine. The opposition here is the more remarkable from Hofmann’s having shaken himself wholly free from the authority of Galen, and, as Slegel says, even admitted the lesser circulation of the blood through the lungs; but this must have been at a later period of his life, for in his works, up to Harvey’s time, the idea he had of the motion of the blood may be gathered from his likening it to a lake or sea agitated by the wind, the veins being the conduits of the nutrient blood, the arteries of the vital spirits. Hofmann was an adversary whom Harvey held worthy of notice; and accordingly we have seen that our immortal countryman took advantage of the opportunity, whilst attending the Earl of Arundel and his party, to visit Hofmann at Nuremberg, and make a demonstration of the new views before him. Unhappily this was done in vain, for Hofmann continued unconvinced, though, towards the end of his very long life, he did show some signs of yielding.[32]

Joannes Veslingius, professor in the University of Padua, and one of the best anatomists of the age, about this time, addressed two letters to Harvey, in which he politely but candidly states his objections to the new doctrine. One great difficulty with Veslingius was the remarkable difference between the colour of the arterial and the venous blood. It did not seem possible to him that the fluid, which was of a bright scarlet in the arteries, could be the same as the dark-coloured fluid which is found in the veins. In the course of his letter, Veslingius takes occasion to animadvert on the uncivil tone and indifferent style of the productions of Primerose and Parisanus.[33]

But the theory of the double circulation was not now to meet with opposition only; the comprehensive intellect that had seized and worked that theorem to a rational demonstration was no longer to be left alone against the world in its defence. Roger Drake, a young Englishman, had the honour of appearing in his inaugural dissertation, proposed under the auspices of Joannes Walæus, the distinguished professor of Leyden, in 1639, as the enlightened advocate of the Harveian views; and in the course of the same year, H. Regius (Leroy) also came forward at Utrecht with certain Theses favorable to the doctrine of the circulation. Ten years had not lessened Primerose’s enmity to Harvey and his views; for, on the appearance of these academical essays, he speedily showed himself again in the field as their opponent, publishing distinct animadversions upon each of the inaugural dissertations in the course of the year.[34] Regius (Leroy), a man of much less mind and information than Drake, if we may decide from their works, was, in turn, not slow to encounter Primerose;[35] and the spirit in which he did so, as well as the temper and taste of the reply which Primerose, true to his controversial nature, very soon produced,[36] may, to a certain extent, be imagined from the titles of their several productions, which are given below.

Still more illustrious advocates of the Harveian circulation presented themselves in Werner Rolfink,[37] professor of anatomy at Jena, and the celebrated Renatus Descartes. Rolfink, from his position and his popularity as a teacher, had immense influence in disseminating the new doctrine over Europe; and Descartes, under the ægis of his powerful name, was no less effective by means of his writings.[38] Opposed in his advocacy of the Harveian views by Vopiscus Fortunatus Plempius, professor of Louvain, Descartes made himself still more thoroughly master of the subject, and when he next appears as its advocate, which he does by and by, he even appeals to the experiments he had made on living animals in support of his convictions and conclusions.

The controversy on the circulation had been carried on up to this time abroad rather than at home; Harvey seems to have won over to his side all the men of his own country who, by their education and acquirements, might have been fitted to array themselves against him: his lectures at the College of Physicians had apparently satisfied all his contemporaries. But now one of Harvey’s own countrymen made his appearance as the vindicator of the circulation from the misrepresentations and misapprehensions of its adversaries. This was Dr. afterwards Sir George Ent, a good scholar, a respectable anatomist, conversant with physical science generally, a gentleman by his position and profession, acquainted with all the leading men of letters and science of his time, and in particular, enjoying the friendship of William Harvey. Ent’s work is entitled ‘An Apology for the Circulation of the Blood, with a Reply to Æmylius Parisanus.’[39] In his letter to Harvey, which stands in front of the work, Ent lets it appear that he was anxious to come before the world as the advocate of the circulation; he first thought of making Primerose the particular object of his animadversions, but as this opponent had already been very effectually handled by Henry Leroy, he preferred taking Parisanus to task, the rather as in dealing with him he could also controvert Primerose where it was necessary.—Ent’s Apology is, undoubtedly, a learned, though perhaps a somewhat pompous and pedantic book; still the writer occasionally shows both wit and fancy in handling his antagonist, and always learning enough in dealing with his subject. “Nothing, indeed,” to quote Dr. Lawrence,[40] “can be more unlike than Parisanus and Ent; and it is not wonderful, therefore, that one utterly ignorant of physical science confronted by one thoroughly conversant therein—that one, without power of utterance, opposed by one gifted with eloquence—that one, sluggish and inert, in the hands of one active and full of energy, should be effectually vanquished and overcome.” We may imagine, nay, we may be certain, that Harvey was not unacquainted with Ent’s purpose to appear as the advocate of his discovery, nor with the Apology before it saw the light.

Having observed the appearance of certain academical dissertations in defence of the circulation, we perceive the apostles of all new truths, namely, the youthful, at work. Were there not successive generations of men, the world would stand still; the death of the individual was not merely a necessary condition to the enjoyment of life by successive generations, but essential also to the onward progress of mankind. No man who had attained to the age of 40 years, it is said, was found to adopt the doctrine of the circulation; it had to win its way under the safeguard of the Drakes and Leroys especially, that is to say, of the youthful and unprejudiced spirits of the age.

Twenty years after the publication of the ‘Exercitatio de Motu Cordis et Sanguinis,’ Joannes Riolanus, the younger, was delivered of his ‘Encheiridium Anatomicum’ (8vo. Lugd. Batav. 1648), in which he makes a vain attempt to supplant the Harveian doctrine by a new and most extraordinary one of his own, so incongruous and unlikely, that in these days we are irresistibly led to form no very high estimate of the intellect that could have engendered it. It looks to us, indeed, at this time, like condescension on the part of the great English anatomist, that he noticed the abortion of such a tyro in animal physics as the French professor here approves himself. Harvey’s genius could surely have felt no real respect for the illogical intellect of Riolan. But Harvey, when he noticed Riolan’s publication, was in want of a good occasion for a farther development of his own views; and so he seized on the Parisian professor, respectable from his position in the university, and as physician to the queen mother of France, and made him his vehicle—his placard bearer. Harvey, besides, was personally acquainted with Riolan, who had accompanied Mary de Medicis to England on a visit to her daughter the Queen of Charles the First; on which occasion Harvey and Riolan had even held conversations on the subject of the circulation, to which it is said that Riolan when face to face with the propounder, made no objection.

Riolan is by no means totally opposed to a circulation of the blood; he would only limit it to certain arbitrary regions, into which he divides the body: whilst it goes forward in one, it has no existence in another. The nature of his ideas can be gathered from Harvey’s comments on them in his First Disquisition, addressed to the Coryphæus of Anatomists, as he politely designates the Parisian professor.

Having disposed of the original notions of the author of the ‘Encheiridium Anatomicum,’ in this first disquisition, Harvey, in his second, returns to his own views, which he proceeds still further to illustrate and confirm by additional arguments, observations, and experiments. In this admirable essay, we obtain innumerable glimpses of the clearness of Harvey’s judgment, of his admirable powers of observation, and the diligent and excellent use he made of them; we at the same time become aware of the great loss we have sustained through the destruction of his Medical Observations. Riolan, in his Encheiridium, proposed to point out in the structure of the healthy body the seats of the various diseases, and to discuss their nature in conformity with the opinions that had been entertained of them. This was obviously at once a barren and an impracticable route: the matters he had in hand could never have been other than abstractions, and his own observations criticisms on opinions, never on facts. How much more natural and judicious the course which Harvey proposes to himself, when he informs us that in his ‘Medical Anatomy’ he meant, “from the many dissections he had made of the bodies of persons worn out by serious and strange affections, to relate how and in what way the internal organs were changed in their situation, size, structure, figure, consistency, and other sensible qualities, from their natural forms and appearances, such as they are usually described by anatomists; and in what various and remarkable ways they were affected. For even as the dissection of healthy and well-constituted bodies contributes essentially to the advancement of philosophy and sound physiology, so does the inspection of diseased and cachectic subjects powerfully assist philosophical pathology.” This was precisely what Morgagni lived, in some considerable measure, to achieve, and it is that which it has been the business of modern pathology, through the illustrious line of the Baillies, Laennecs, Andrals, Louis, Cruveilhiers, Carswells, Richard Brights, and many others, to render more and more complete.

Riolan never replied to Harvey; but neither did the Parisian Professor attempt to vindicate his views, nor did he exhibit such candour as to own himself otherwise convinced or converted. His doctrine had no abettors, and never bore fruit; it stood a barren ear amidst the lusty, green, and copious harvest, that had already sprung up and overspread the lands.

Harvey must now, indeed, have seen his views assured of general reception at no distant date. The same year in which he himself answered Riolan, Dr. James de Back, of Amsterdam, published his work on the Heart,[41] which is written entirely in harmony with the Harveian doctrines, and the celebrated Lazarus Riverius, Professor of Medicine in the University of Montpellier, publicly defended and taught the circulation of the blood.[42] The following year, Paul Marquard Siegel, of Hamburg, produced his commentary on the Motion of the Blood,[43] in which he addresses himself particularly to a refutation of Riolanus, whose scholar he had been, and at the same time shows himself so thoroughly at home in the general question, that he is able to throw additional light on it by new and ingenious considerations and experiments.

Harvey appears to have been pleased with Slegel’s production; for by and by he sends the Hamburger his new work on Generation, accompanied by an admirable letter, which has happily been preserved.[44] No one in reading that remarkable epistle could suppose that the pen which set it down was in the hand of a man in the 75th year of his age.

The young men of 1628 and 1630, who had been educated in unbelief of the circulation, were now coming into possession of professorial chairs and places of distinction; and having long escaped from leading-strings and made inquiry for themselves, were beginning in many of the European universities to proclaim the better faith through further knowledge that had sprung up within them. Harvey had himself received the seeds of his discovery in Italy; but the fructifying mother was slow to recognize him whom she had so powerfully concurred to form. It was not till 1651 that Harvey’s views were in any way admitted beyond the Alps, when Trullius, a Roman professor, expounded and taught them. About the same time, John Pecquet,[45] of Dieppe, and Thomas Bartholin, the Dane,[46] men of original mind in the one case, of extensive learning and great research in the other, gave in their adhesion to the new doctrine, and spread it far and near by their writings. The victory for the circulation may finally be said to have been won, when Plempius, of Louvain, the old antagonist of Descartes on the subject, retracted all he had formerly written against it, convinced of its truth, as he so candidly informs us, by the very pains, he took to satisfy himself of its erroneousness, and publicly proclaimed his conversion: “Primum mihi hoc inventum non placuit,” says the worthy Plempius—“This discovery did not please me at all at first, as I publicly testified both by word of mouth and in my writings; but by and by, when I gave myself up with firmer purpose to refute and expose it, lo! I refute and expose myself, so convincing, not to say merely persuasive, are the arguments of the author: I examine the whole thing anew and with greater care, and having at length made the dissection of a few live dogs, I find that all his statements are most true.”[47]

From the first promulgation of the doctrine of the circulation, its progress towards ultimate general acknowledgment can scarcely be said for a moment to have been interrupted. The hostility of the Primeroses and Parisanuses and Riolans never interfered with it in fact; the more candid spirits were rather led to inquire, by the virulence of these weak and inconsistent opponents, who thus hastened the catastrophe of their own discomfiture, and the triumph of the truth. If men’s minds were once in danger of being led astray, it was only for an instant, and not so much through the opposition of enemies, as by an erroneous generalization, which a short interval of time sufficed to correct. Cæcilius Folius, a Venetian physician, having met with one of those anomalous instances of pervious foramen ovale in an adult, immediately and without looking farther, jumped to the conclusion that this structure or arrangement was normal, and that the blood passed in all cases by the route he had discovered, from the right to the left side of the heart. Many Italians received with favour the account which Folius immediately published of his discovery;[48] and the natural philosopher, Gassendi, having about the same period had another instance of the kind which Folius encountered, shown to him, concurred with this writer in his views, and by a variety of arguments and objections, strove to damage, and did temporarily damage, the Harveian doctrine.[49] But this was only for a brief season; for Domenic de Marchettis[50] soon after showed that Folius had mistaken an extremely rare occurrence for a general fact, and that if the open foramen ovale might afford a passage from the right to the left side of the heart in one case, closed it would suffer no such transit in hundreds of other instances. Gassendi, moreover, by getting still more out of his depth, soon afterwards showed that familiarity with general physics did not imply a particular knowledge of anatomy, nor give the power of reasoning sagely on subjects of special physiology; so that in his eagerness to assail Harvey he did injury in the end only to his own reputation. In short, Harvey in his lifetime had the high satisfaction of witnessing his discovery generally received, and inculcated as a canon in most of the medical schools of Europe; he is, therefore, one of the few—his friend Thomas Hobbes says, he was the only one within his knowledge—“Solus quod sciam,”[51] who lived to see the new doctrine which he had promulgated victorious over opposition, and established in public opinion. Harvey’s views, then, were admitted; the circulation of the blood, through the action of the heart, was received as an established fact; but envy and detraction now began their miserable work. The fact was so; but it was none of Harvey’s discovering; the fact was so, but it was of no great moment in itself, and the merit of arriving at it was small; the way had been amply prepared for such a conclusion.

Let us look as impartially as we may at each of these statements.

They who deny the originality of Harvey’s induction, very commonly confound the idea of a Motion of the blood, with the idea of a Continuous Motion in a Circle. It would seem that even from remote antiquity, and by common consent, mankind had recognized the blood to be in motion. We have this fact declared to us by all antiquity, and it is even particularly referred to in various passages of the grand observer of his age, the depositary of the popular science of all preceding ages—Shakespeare. Brutus speaks thus to Portia: