With reference to the greater or systemic circulation, again, Cæsalpinus speaks of the swelling of the veins between the circle of pressure and the extremities of the vessels, when a ligature is thrown round a limb; and he even goes so far as to state that the common opinion which admitted a progressive motion—i. e. a motion from trunks to branches—of the blood in the veins was erroneous. Did we go no farther we should be led to conclude, as in Columbus’s case, that Cæsalpinus believed in the continuous movement of the blood in the veins in one direction only; and, as he has already spoken of the exit of the blood from the left ventricle, and of its reception by the aorta for general distribution, it might forthwith be inferred that, possessed of the essential elements of the greater circulation, he must, as matter of course, have been familiar with this as an ultimate result. And such an inference has indeed been drawn for him by high authority; but Cæsalpinus came not himself to any such conclusion; it was arrived at by others in his behalf, and after the lapse of almost a century from the date of his first publication. When we find Cæsalpinus, in other and closely connected passages of his writings, singing the old cuckoo note about a flux and reflux of the blood in the veins, and even using the accredited word—Euripus—to express his idea of its tide-like nature; when we further perceive that he was ignorant of the existence of the valves of the veins, and finally arrive at his explanation of the cause of the swelling which takes place in the veins of an extremity beyond a ligature,—the cause with him consisting in an effort of the blood to get back to the focus or centre, lest, through the compression of the veins, it should be cut off and suffocated,—we not only feel that we were warranted in entertaining a wholesome scepticism of the conclusion come to by the admirers of Cæsalpinus in regard to his knowledge of a circulation of the blood; but waxing in our infidelity as we become farther acquainted with his thoughts on the constitution of the blood, we find everything opposed to the likelihood of his having arrived at the same result as Harvey; and, at length, we discover that he neither had nor could have had any true knowledge of the circulation. Starting from the Aristotelian doctrines of growth and nutrition (of which so much will be found in Harvey’s work on Generation), Cæsalpinus held that there were two kinds of blood, one for the growth, another for the nourishment of the body. The blood which went to augment the body, and which he designated alimentum auctivum, or aliment of increase, flowed from the liver into the vena cava, which he seems to have thought was connected with the heart only, ut inde virtus omnis a corde descendat—that a sufficiency of virtue might be thereby communicated to it. The auctive blood, he farther thought, was attracted into the ventricles of the heart by the inherent heat of the organ. The dilatation of the heart and arteries he imagined to be due to “an effervescence of the spirit;” and the cause of their “collapse”—not systole, be it observed, in the active sense—was the appropriation by the parts of the body of the nutritive and augmentative matter. Again, though Cæsalpinus speaks of the intercommunication of the minute arteries and veins, he still thought that it was only during sleep that the blood mixed with the spirits passed from the former into the latter class of vessels; for it is during sleep, he says, that the veins become distended, whilst the pulsations of the arteries are then moderated. He plainly sees no connexion between a delivery by the artery and a filling by the vein. It is along with all this, and as if to settle the question of the kind of knowledge Cæsalpinus had of the movement of the blood, that he uses the old word Euripus, to express his idea of its alternating or tide-like motion.
Cæsalpinus, let us add, had no conception of the heart as the efficient cause of any motion which the blood might have. In the often-quoted passage from the work ‘De Plantis,’[57] it is still the spirit inherent in, or associated with, the blood, that is the cause of its motion.
Cæsalpinus, consequently, tried by a very moderately searching criticism, presents himself to us as but very little farther advanced than the ancients in his ideas on the motion of the blood.—The interpretation which successive generations of men give to a passage in a writer, some century or two old, is very apt to be in consonance with the state of knowledge at the time, in harmony with the prevailing ideas of the day, and, doubtless, often differs signally from the meaning that was in the mind of the man who composed it. The world saw nothing of the circulation of the blood in Servetus, Columbus, Cæsalpinus, or—Shakespeare, until after William Harvey had taught and written.
The truth is, that some of the foremost grounds of Harvey’s claims to rank as a discoverer are very commonly overlooked. We always associate his name and fame with the development of the ultimate fact of the circulation of the blood. But Harvey, as a step to this conclusion, first demonstrated the heart as the means by which the circulation was effected; and he farther showed that there was but one kind of blood, common to both the arteries and the veins. Up to his time the heart was regarded as the passive cistern of the blood, and the elaboratory of the vital spirits; it was not known as the moving instrument in any efflux or reflux of the blood, or even of any lesser circulation that had been previously asserted or conjectured. The moving power was still the respiratory act. Harvey may be said to have first broached, as he also essentially completed the physiology of the heart’s actions. The circular motion of the blood followed as a necessary corollary from these. The “motion of the heart” has even precedence in the title of his immortal work; the chapter in which he first enters properly on his subject (Chap. 2), is devoted to its consideration. And then, no physiologist up to Harvey’s time had questioned the existence of two kinds of blood, one appropriate to each order of vessels, and answering different ends in the economy.
The only name still wanting in this historical sketch, till we come to Harvey, is that of Fabricius of Aquapendente, his teacher in anatomy. Fabricius had given particular attention, among other subjects, to the anatomy of the valves of the veins, which he entitled ostila venarum. Fabricius, indeed, possessed so thorough a knowledge of the valvular elements of the vascular system, that it is really astonishing, as an able writer[58] has remarked, that he should not have had clearer ideas on the functions, among other things, of the pulmonary veins, and should have continued a rigid adherent to the prejudices which prevailed before his time. Fabricius could observe, and he could describe; but he wanted the combining intellect that infers, the imagination that leads to new ideas—to discovery. Though he did little himself, however, to advance the sum of human knowledge, he proved a tooth in the wheel that has since put in motion the whole machinery of modern medical science. He it was who sowed the seed, little dreaming of its kind, which, finding one spot of congenial soil, sprung up a harvest that has continued to nurture the world of physiological science to the present hour.[59]
Having now disposed of the claims that have been set up in behalf of one or another as the discoverer of the circulation, and shown, we trust satisfactorily, that these are all alike untenable, we should now proceed to discuss the question of the cui bono?—but this meets us in so forbidding an aspect, brimful as is our mind with a sense of the all-importance of the knowledge we had from Harvey, and seems so little to belong to our subject, that we gladly pass it by unnoticed; though it be only to find ourselves encountered by that other topic, but little more congenial to our mood of mind and intimate persuasion: The merit of Harvey as a discoverer. Few, very few have been found to question this; but as one man of undeniable learning and eminence in his profession,[60] has very strangely, as it seems to us, been led to do so, it will not be impertinent if we cast away a few words on this matter.
Discovery is of several, particularly of two kinds: one sensible or perceptive; another rational or inductive; the former an act of simple consciousness through an impression made on one or more of the senses; the latter a conclusion come to by the higher powers of the understanding dealing with data previously acquired by the senses and perceptive faculties.—We look through a telescope, for example, and we perceive a star which no one else had seen before; we note the fact, and so become discoverers of a new star. The merit here is not, surely, very great, though the added fact may be highly important. Again, one of the planets is subject to such perturbations in its course that to compose exact tables of its orbit is held impossible. These perturbations are referable to none of the known perturbing causes. A great astronomer suggests the influence of an exterior and unknown planet as their cause. A consummate mathematician and physical astronomer makes trial of this suggestion: he assumes the ascertained perturbations as elements, he combines these under the guidance of knowledge and reason, and at length he says, if the cause suggested be well founded, there or thereabouts must it exist; and lo! on turning the far-seeing tube to the point in space which he had indicated, there in verity gleams a new world, then first seen, though launched by God from Eternity to circle on the verge of our creation; and he who bade us look becomes the discoverer of a new planet. Who will dispute the merit here? Truly, man does show the God within him when he uses his faculties—God-like in themselves—in such God-like fashion. But Harvey’s merit, according to our idea, was of the selfsame description in another sphere. The facts he used were familiarly known, most of them to his predecessors for nearly a century, all of them to his teachers and immediate contemporaries; yet did no one, mastering these facts in their connexion and sequence, rising superior to prejudice, groundless hypothesis, and erroneous reasoning, draw the inference that now meets the world as irresistible, until the combining mind of Harvey gave it shape and utterance. To our apprehension Harvey was as far above his fellows as the eye of poetic intelligence, that exultingly absorbs the beauties of the starry sky and the green earth, is above the mere physical sense that distinguishes light from dark. The late Dr. Barclay, a fervent admirer of Harvey, whose name he never uttered without the epithet immortal, has put the question of Harvey’s merit both happily and eloquently, and it affords us pleasure to quote the passage from the writings of our old and honoured teacher in anatomy. “The late Dr. Hunter,” says Dr. Barclay,[61] “has rather invidiously introduced Harvey along with Copernicus and Columbus, to show that his merit as a discoverer was comparatively low. But what did Copernicus, and what did Columbus? Not in possession of more numerous facts than their contemporaries, but endowed with nobler and more vigorous intellects, the one developed the intricate system of the heavenly bodies and the other discovered an unheard-of continent. Was it not in the same way, by the exertion of superior intellect, that Harvey made his immortal discovery? I know not what has happened in the world unseen; but if I may judge from the records of history and the annals of fame, the spirit of Bacon, the spirits of Columbus, Copernicus and Newton have not been ashamed to welcome and associate with the congenial spirit of Harvey.” To this fine passage there is little to be added: Harvey’s discovery was of the rational and inductive and therefore higher class, according to our estimate; it was made in virtue of the intellectual powers which peculiarly distinguish man, possessed in a state of the highest perfection.
THE WORK ON GENERATION.
In our account of Harvey’s public career we found him busy with the subject of Generation at Oxford in 1642; but he had certainly turned his attention that way at a much earlier period, for one of the chief causes of his regret, as expressed to Dr. Ent, for the destruction of his papers during the civil war, is the loss of his Observations on the Generation of Insects, which could only have been made and reduced to form many years previously, probably before his engagement to accompany the Duke of Lennox on his travels. And then we see that all his notes on the gestation of the hind or doe were made in the palmy days of the first Charles, before the differences between him and the people of these countries had come to the arbitrement of arms. Harvey probably occupied a good deal of his leisure in arranging and writing the work on Generation, after quitting the service of Charles in 1646; his practice at this period was not extensive, and he seems to have passed much of his time in the country. Harvey appears to have been little inclined to the publication of this work, and only to have ventured it out of his hands with reluctance. Without the solicitations of Ent, indeed, it would certainly have been left unpublished during his lifetime. Ent, however, succeeded in carrying off the prize which his illustrious friend had showed him, and lost no time in getting it into types, taking on himself the task of correcting the press, and sending it forth according to his own ideas in fitting form, with a frontispiece, and a highflown dedication to the President and Fellows of the College of Physicians. Ent’s account of his interview with Harvey on the occasion of obtaining his consent to the publication, though highly theatrical, is still extremely interesting. Saluting the great anatomist, and asking if all were well with him, Harvey answers, somewhat impatiently as it seems: “How can it, whilst the Commonwealth is full of distractions, and I myself am still in the open sea? And truly,” he continues, “did I not find solace in my studies, and a balm for my spirit in the memory of my observations of former years, I should feel little desire for longer life.” ([p. 145].) Let the reader turn to the page from which the above quotation is taken, and to the one which follows it, for thoughts and views that clearly bespeak the greatness of intellect, the nobleness of sentiment that distinguished William Harvey. When Ent proceeds to say that the learned world, aware of his indefatigable industry, were eagerly looking for other works at his hands, the fervid genius of the poet or discoverer still appears in his reply: “And would you be the man,” said Harvey, smiling, “who should recommend me to quit the peaceful haven, where I now pass my life, and launch again upon the faithless sea? You know full well what a storm my former lucubrations raised. Much better is it oftentimes to grow wise at home and in private, than by publishing what you have amassed with infinite labour, to stir up tempests that may rob you of peace and quiet for the rest of your days.” ([p. 147].) By and by, however, he produces his Exercises on the Generation of Animals, and though he makes many difficulties at first, urging, among other things, that the work must be held incomplete, as containing nothing on the generation of insects, Ent, nevertheless, prevails in the end, and receives the papers with full authority, either speedily to commit them to the press, or to delay their publication to a future time. Ent set about his office of midwife, as he has it, forthwith, and the following year (1651) saw the birth of the work on Generation.
Physiological science generally was not sufficiently advanced in Harvey’s time to admit of a truly great and enduring work being produced on a subject so abstruse, and involving so many particulars as that of Generation. On the doctrine of the circulation the dawn had long been visible; Harvey came and the sun arose. On the subject of animal reproduction, all was night and darkness two centuries ago; and though the light has still been waxing in strength since Harvey wrote, it is only in these times that we have seen it brightening into something like the day. In Harvey’s time the very means and instruments that were indispensable to the investigation were not yet known, or were used of powers inadequate to bring the prime facts within the cognizance of the senses. Harvey doubtless did as much as any man living could have accomplished when he wrote. He announced the general truth: Omne animal ex ovo; he showed the cicatricula of the egg as the point where the reproductive process begins; he corrected numerous errors into which his master Fabricius had fallen; he further pointed out the path of observation and experiment as the only one that could lead to satisfactory results in the investigation of a subject which gradually displayed itself as one of natural history; and, it may be added, by his wanderings in the labyrinth of the metaphysics of physiological science, he did enough to deter any one from attempting to tread such barren ground again. In his work on the Heart and Blood, Harvey had all the essential facts of the subject clearly before him, and he used them at once in such masterly-wise, that he left little or nothing for addition either by himself or others. Secure of his footing here, he could well dispense with “vital spirits,” “innate heat,” and other inscrutable agencies, he could leave “adequate and efficient causes,” and other metaphysical phantoms on one side—it was physics that he was dealing with, and the physician was at home. With the information we now possess, we see clearly how indifferently weaponed was the physiologist of the year 1647 for encountering such a subject as Animal Generation; a Leeuwenhoek and a De Graaf, a Spallanzani and a Haighton, a Wolff, a Purkinje, a Von Baer, a Valentin, a Rudolph Wagner, a Bischoff, and many more, had successively to appear, before the facts of the subject could be ascertained, and a Schleiden and a Schwann were further necessary as ultimate interpreters of the things observed before they could be either rightly or wholly understood. No wonder then that The Physiologist of the 17th century, meets us in the guise of one rather puzzled with the burthen he has made up his mind to bear, and, contrary to his former wont, eking out the lack of positive knowledge by reiterated disquisitions on topics where certainty is unattainable.