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It is a happy moment for a physiologist when the train which is bearing him across the luxuriant plain of Venetia stops at the cry of "Padova!" If he have not informed himself too thoroughly about the sights which he will see at the Paduan University, he will enjoy his own surprise when he is ushered into the Anatomical Theater of Fabricius ab Aquapendente—a room in which standing-places rise steeply, tier above tier, entirely around a small central oval pit. Looking down into this, as he leans upon the rail, the traveler will realize with sudden pleasure that William Harvey, when a medical student, may often have leaned upon the self-same rail to see Fabricius demonstrate the anatomy of man. The place looks fit to have been a nursery of object-teachers, for it is too small to hold a pompous cathedra; and the veteran to whose Latin the young Englishman listened must have stood directly beside the dead body. To an American, musing there alone, the closing years of the sixteenth century, the last years of Queen Elizabeth of England, which seem so remote to him when at home, are but as yesterday.

Recent, indeed, in the history of medicine is the year 1602, when Harvey received his doctor's degree at Padua and returned to London; but for all that we are right in feeling that our day is far removed from his. The tireless progress of modern times has swept on at the charging pace; but in Harvey's time books were still a living force which had been written in days five and six times as far removed from the student of Padua as he from us. Galen, the Greek who practised medicine at imperial Rome in the second century of the Christian era; Aristotle, who had been the tutor of Alexander the Great five hundred years before Galen, when Rome was but a petty state warring with her Italian neighbors;—these ancients were still great working authorities in Harvey's day.[1]

It is against this persistent glow of the Greek thought that Harvey stands out so vividly as the first great modern figure in physiology. But it rather heightens than lowers his achievement that it was by the ancient glow that he saw his way forward, admiring the past, but not dazzled by it. In his old age he bade a young student "goe to the fountain head and read Aristotle, Cicero, Avicenna"; and in talk with the same youth Harvey called the moderns by a name so roughly contemptuous that it will not bear repeating.[2] Yet in his old age, in the very act of extolling the ancients, he wrote as follows:[3]—

"But while we acquiesce in their discoveries, and believe, such is our sloth, that nothing further can be found out, the lively acuteness of our genius languishes and we put out the torch which they have handed on to us."

The Anatomical Theatre at Padua, where William Harvey listened to the lectures of Fabricius ab Aquapendente.

It was in 1628, the year of his fiftieth birthday, that Harvey published, at Frankfort-on-the-Main, his famous Latin treatise entitled: "An Anatomical Exercise on the Motion of the Heart and Blood in Animals." A reader of to-day will be inclined to skim rapidly over the Introduction to this treatise and over much in the last three chapters; and probably he will take only a languid interest in the two brief Latin treatises which Harvey published in defense of the circulation, after more than twenty years of silence, in his seventy-first year, at Cambridge in 1649; these treatises being entitled: "Two Anatomical Exercises on the Circulation of the Blood, to Johannes Riolanus, Junior, of Paris."

The demonstration of the circulation in the treatise of 1628 is so irresistible that the ancient strongholds of belief crash to the ground at that summons like the walls of Jericho, and it seems a waste of time to scan the fragments. But for all that, the edifice which had stood for more than thirteen centuries was a goodly structure; and whoever shall have read Aristotle and Galen at first hand and shall then return to Harvey, will read with interest what the same reader treated as a mere foil for the great demonstration; and will realize that the irresistible quality of the latter is shared by Galen's demonstration that blood is naturally contained in the arteries.[4] Moreover, it will be seen that if the Greek of the second century could, like Harvey, appeal to observation and experiment, the English physician of the Renaissance, the student of Cambridge and Padua, was an apt pupil of the Greeks. Harvey could, and frequently and naturally did, view things from a Greek and ancient standpoint when proof of their nature was unattainable. This is to be seen not only in his earlier and later exercises on the circulation, but also in his last work, his "Exercise on the Generation of Animals" with appended essays, published in Latin at London in 1652, in Harvey's seventy-third year, two years after the appearance of the exercises addressed to Riolanus. This treatise On Generation deals also at various points with the blood and the circulation, as do in addition Harvey's published Latin letters. We shall find, too, the same leaning upon the ancients as immediate precursors in thinking, if we turn back from the publications of Harvey's old age to the very first written words of his which we possess, private lecture notes jotted down by him in his thirty-seventh year for use in 1616—notes happily printed and published in 1886.[1] In these notes, written more than eleven years before the publication of his most famous treatise, he sets forth for the first time, though briefly, the circulation of the blood, that physiological truth which to my mind is completely and indisputably Harvey's own discovery. It is with Harvey as the interpreter, not the maker, of this discovery, that I shall venture to deal in this paper.

In his old age the great discoverer recorded his own attitude, as an interpreter, in the following words:—

"That freedom which I freely concede to others, I demand with good right for myself also; liberty, that is, in dealing with obscure matters, to bring forward, to represent, the truth, that which seems probable, until the falsity thereof shall clearly be established."[5]

In 1636, eight years after he had published the treatise which now seems so convincing, Harvey was in Nuremberg and wrote to Caspar Hofmann, M.D., a professor of repute who lived there, offering to demonstrate the circulation to him. In his letter Harvey quotes impatient words of his German colleague, which show that in the face of proof the circulation still seemed to some men of high standing too useless to be true. Harvey says to Hofmann:—

"You have been pleased to reproach me rhetorically and chastise me tacitly as one who seems to you 'to accuse and condemn nature of folly as well as error, and to impose the character of a most stupid and lazy craftsman on her, since he would permit the blood to relapse into rawness and to return repeatedly to the heart to be concocted again; and, as often, to the body at large to become raw again; and would permit nature to ruin the made and perfected blood in order that she may have something to do.'"[6]

To this attack Harvey calmly rejoins as follows, speaking of the blood:—

"As to its concoction and the causes of this its motion and circulation, especially their final cause, I have said nothing, indeed have put the subject by entirely and deliberately; as you will find set down in plain words and otherwise if you will be pleased to read again chapters VIII and IX."[7]

More than twelve years later still, in defending the circulation against Riolanus, Harvey finds it necessary to say:—

"Those who repudiate the circulation because they see neither the efficient nor the final cause of it, and who exclaim 'Cui bono?'—(As to which I have brought forward nothing so far; it remains to be shown)—plainly ought to inquire as to its existence before inquiring why it exists; for from the facts which meet us in the circulation regarded as existing, its uses and objects are to be sought."[8]

In spite, however, of these disclaimers of formal position Harvey had repeatedly intimated, by the way, what was crossing his mind as to the meaning of the circulation, to set forth the proofs of which had been his main concern. Even in the eighth chapter to which Harvey appealed in support of his disclaimer Hofmann could have pointed to two passages as affording from his standpoint a basis for his attack. In the second and shorter of these two passages Harvey says of a vein as compared with an artery:—

"This is a way from the heart, that to the heart; that contains cruder blood, effete and rendered unfit for nutrition; this, concocted, perfect, alimentary blood."[9]

Harvey, indeed, as we shall find abundant evidence, was both an observer and a speculator. In the latter rôle he was not far removed from his physiological predecessors of two thousand years; as an observer it was his great merit to lead the physiologists of his time and to point out to those of all later centuries the path which they must follow.