CHAPTER XXXII

ANATOMY, PHYSIOLOGY, AND DISEASE

LEONARDO interested himself efficiently in all physical science; and, along the pointings of his divers activities, one may follow the more special investigations of men who shared the same scientific spirit, pursued a like method, and would not acquiesce in the dicta of authority. It was not these dicta themselves, but rather their acceptance without testing their truth, that barred the way to free research. The men who were interested in the phenomena of the natural world, including the human body, differed among themselves in their mental processes and affinities; some of them indulged in the vagaries of loose speculation, or were affected by the superstitions or baseless sciences of the time, especially astrology; while some might follow more seriously and exclusively the method of direct observation and experiment, and the conclusions of rational or mathematical deduction. It is hazardous to draw lines of division among them; for the habits of the most effective intellects of the sixteenth century inclined toward many a slant that distorted their better thinking and retarded the progress of their more veritable knowledge. Those who most intelligently drew their conclusions from their own and others' observations are best entitled to be called men of science. Such did in fact enlarge their knowledge of the visible and tangible world, including the human organism. Their efforts did much toward placing, or replacing if one will, the physical sciences upon such bases as the Greek physicists as well as Leonardo would have approved and modern scientists might sanction.

In regard to these scientists and quasi-scientists of the sixteenth century, the matter of human interest lies in their intellectual attitude and the method of their studies and investigations. To what extent do they represent

a change from the attitude toward fact and method of investigation followed in physical studies say by Albertus Magnus, or say, by Roger Bacon; or again by Albertus of Saxonia or Nicholas of Cusa? These four men differed among themselves in their ways of seeking truth; for in the main Albertus Magnus was a scholastic commenting on Aristotle, while Roger Bacon professed to set forth a new method and to discard much that struck him as perverse. Albertus of Saxonia was an observant physicist, although he still cast his writings in the form of commentaries on the works of Aristotle. Nicholas of Cusa, a later man, has the book-learning of his time, and knows the old authorities; but his face is half turned from them toward the new vistas, and he deeply ponders upon conceptions of the universe which shall tally with the needs and tendencies of his own thinking. He is quite as much of the coming time as of the Middle Ages; so indeed was Albert of Saxonia, and in another manner Roger Bacon. The minds of all of them, of course, were filled with thoughts and expressions from the past, and in the main their knowledge was its knowledge, which had come to them. But in their several manners they were also thinking for themselves and looking upon things about them and the revolutions of the stars above, which are beginning to shake their assurance of the primacy of their own Earth-globe. From them the way up, or the way serpentine, to the men of the sixteenth century, has many slopes and curvings, but no sudden break, nor even corners so sharp as to keep the old vehicles of thought from turning them.

The ways of human progress in knowledge are continuous beneath the apparently broken surface of the road. Thoughts may seem new and methods novel, but within them as their efficient moving core lies the self-transmission of the past, the moving content of knowledge and forms of thought and expression, as-well as the impulse to perpetuate and add to it. This will remain true, although some of our sixteenth century men will show methods making a departure from those preceding them, while others show a more confused amalgam of the old

thoughts and methods with their own by no means consistent thinking.

A few years after Leonardo's death the method of direct examination of the pertinent physical facts was established in the most direct and simple form in that very science of anatomy to which he had set himself so zealously. Andreas Vesalius was the author of this achievement. Judging by results and their continuity, it was he, rather than Leonardo, who founded the modern method and science of anatomy, and prepared the way for physiology. He was born at Brussels in 1514, just as the bells were ringing out the old year. For genera

tions his forbears had been doctors. He went to school at Louvain, and entered the university. But his constant and passionate occupation was the dissection of animals. In his eighteenth year he made his way to Paris to hear Jacobus Sylvius (Jacques Du Bois) the most famous master of anatomy at that time. Sylvius was a hard conservative, who taught Galen, and used dissections to illustrate that great authority rather than as independent means of gaining knowledge. Vesalius could not endure that Sylvius should lecture from a book while barbers clumsily cut up a human body or far more frequently a dog's. What knowledge could be gained from having the roughly extracted viscera shown to him? This masterful auditor insisted upon conducting the dissection himself. "I had to put my own hand to the business." 1 Outside of the lecture-room, Vesalius dissected dogs, and haunted the cemeteries, where there were piles of human bones. He became so familiar with them that he could recognize any part of the human skeleton by touch, and name it with his eyes blindfolded.

After some three years of medical study in Paris, Vesalius returned to Louvain, and then went to Venice and soon to Padua, where at the end of the year 1537 he was made professor in the university. He was scarcely twenty-three.

1 The quotation is from the preface of Vesalius' Fabrica humani corporis. See Sir M. Foster's Lectures on the History of Physiology (Cambridge, Eng., 1901). My facts as to Vesalius are gleaned from M. Roth, Andreas Vesalius Bruxellensis (Berlin, 1892).

Quickly casting aside "the ridiculous method of the schools," he demonstrated and dissected before his students, practicing also the vivisection of animals. But

he used Galen in lecturing, at least until he became convinced that Galen had made his dissections and descriptions from apes, rather than from human bodies. After that, braving all opposition, he gradually freed himself and his demonstrations from the older author; and even used the bodies under dissection to show the many errors in Galen's descriptions when applied to the parts and organs of the human body. He was now demonstrating and lecturing from the facts alone, and from books no longer. He had five hundred students, and was already known beyond the university through his reputation and his Anatomical Tables, which circulated widely.

In order to establish the validity of his method before the learned world he set himself to the preparation of his great book, the Humani Corporis Fabrica. With it he composed a simpler Epitome for less advanced students. He set out for Basel to publish these works; and in 1543 the Fabrica was printed in seven hundred folio pages, with many illustrations. The text presented careful and minute descriptions of the parts and organs of the body, and then compared Galen's defective accounts of the same. Thus while setting forth a corrected and improved anatomy, it demonstrated Galen's errors by appealing not to authority but to the facts carefully presented. It was shown that Galen had made his descriptions from the dissection of apes and not of human bodies. Vesalius pointed to the Alexandrian physicians who centuries before Galen had really studied human bodies. By such arguments and biting sarcasm he sought to break the spell of Galen's infallibility. His polemic was directed as well against opponents, named and unnamed, who still relied upon authority in the face of facts. The attack was direct, the method incontestible; if only students could be prevailed upon to use their hands and eyes and reason.

This was the difficulty, since it meant a reversal of the long habit of seeing through others' eyes, and thinking in

the forms of the traditional knowledge. Appeals to fact have proved futile quite as often as they have succeeded. But the time was ripe for the new method of investigation. Against storms of opposition, the book won such success that never more could professors at good universities read aloud from Galen, while barbers ignorantly cut up animals or even human bodies, and all present remained ignorant of the discrepancies between the facts before their eyes and the texts sounding in their ears. Vesalius's book was the foundation stone of a new anatomical science based upon dissection, and again dissection: - the dissection of human bodies and the vivisection of living animals.

The last was to be of enormous importance. For Vesalius's book did not stop with strictly anatomical descriptions, but considered, none too successfully, the functions of the organs: in a word, it proceeded naturally from anatomy to physiology. Its tone and contents were in themselves an argument against the many superstitions touching the care of health and the cure of disease. Its preface set forth the long decline of medicine and the contempt into which it had fallen: all due to the ignorance of the human body which had prevailed ever since physicians ceased to make dissections with their own hands.

Vesalius was not yet thirty, and his work as the founder of modern anatomy was done. Angered by the abuse which followed the publication of his Fabrica, he burnt the records of his further investigations, and became court physician to the Emperor Charles V. Intelligently and fruitfully he practiced medicine and surgery; but never again gave himself to systematic dissection. He brought out a second edition of his Fabrica, making some corrections and adding observations from his experience. He was not fifty when he died.

But others were ready to take up the study of “that true bible," as he called it, as he called it, "the human body and the nature of man." Its study was to embrace the function as well as structure of the organs. Galen taught that the blood passed from the right to the left side of the