Vesalius on the authority of the authorities

he Fabrica is a polemical book with two targets: contemporary 16th century orthodoxy and the ancient authorities. Because so much of the anatomical doctrine taught in the universities of Europe was based upon Galen, the Hippocratics, and other ancient authorities, Vesalius did not often have to distinguish between the two objects of his scorn.

The polemical style was already a part of the Galenic tradition in which Vesalius wrote. All he had to do was adopt the style of the authority — Galen — whose authority he was trying to overthrow. From the beginning of his career as a lecturer at Padua, Vesalius had made a splash demonstrating errors of Galen which were being taught by others as gospel. Baldasar Heseler's eyewitness report of of Veslaius' first public anatomy as Bologna in 1540 (Eriksson 1959) shows how confrontational Vesalius could be. The entertainment value of statements attacking the previously unimpeachable authorities of the ancient world cannot be ignored. Here are some samples from the Fabrica.
Why, I pray, should we not say those anatomists are rough and untrained who have passed on to posterity Galenic descriptions that are false in some respects and in most cases apply to apes and dogs but not humans, as if they had observed them in man, and were in no way afraid, like scribes, to enumerate things they never saw even in a dream, and often misunderstood in Galen's books? Where, I ask, after the times of Galen, is mention made of the sacrum and coccyx other than what is passed down by a Galen who is inconsistent in various places? Yet none altogether fits the picture of human bone. For the present, let us dismiss the remaining Galenists, who have obstructed rather than aided the understanding of human anatomy, and reconsider at greater depth the opinion of Galen, who is easily the leader of all professors of anatomy, lest we seem discreditably to have neglected his authority as well. (Bk. I Chapter 18)

It is commonly believed that men lack a rib on one side, and that men have one rib fewer than women. This is plainly absurd, even if Moses did say in the second chapter of Genesis that Eve was created by God out of Adam's rib. Granted that perhaps Adam's bones, had someone articulated them into a skeleton, might have lacked a rib on one side, it does not necessarily follow on that account that all men are lacking a rib as well. Aristotle attributed only eight ribs to humans, and was ready to allow that certain members of the race of the Turduli were born with only seven ribs on each side, provided he established this on the actual testimony of some suitable authority. But as in the latter instance Aristotle was willing to support his opinion only with the testimony of others, it is also not unlikely that in the former instance he ascribed eight ribs to man on hearsay evidence, and in this manner wrongly handed down to us something he had not seen. For if we discover that he was suppositious so many times concerning the fabric of man, what judgement shall we make about the rest of his research into animals? (Bk. I Chapter 19)

I believe that hereafter students of Aristotle and Galen will compare the bones of humans, quadrupeds, and even birds, and will investigate how we move when supported on four legs, as it were, in what manner a cat or dog sits, or is supported when erect against a wall, and how they correspond or differ in each distinct feature, so that students of natural science may more correctly consider the opinions of such great men that have been studied so far and wide, and at last be admonished and recognize how manifestly the similarity of such bones refutes them, and how the anatomical doctrines of Aristotle and Galen — and even less of Plato — were not spoken by the oracle. (Bk. I Chapter 33)

Such persons as were born only for the ostentation of their professorial chair ought surely to consider carefully that Galen spoke about his monkeys, not about human beings.
(Bk. II Chapter 5)

But what is the point of assembling such reasoning to overthrow Galen's opinion? A dissection carried out by careful students warned in advance seriously undermines not only this doctrine but others as well that are read everywhere in De placitis Hippocratis et Platonis; a great many of these are cheerfully accepted by doctors because of their ignorance of dissection and the excessive faith that we have in writers as if they were oracles of Apollo. For the present I shall be happy to leave behind the opinions of Galen and describe the ascending part of the vena cava so that my account may tell only what is true and not grow oversize or be interrupted because of Galen. (Bk. III Chapter 7)

Readers of the Fabrica will find that it is not just science. It is a rhetorical performance in which the most elaborate and difficult Latin is reserved for passages where Vesalius goes on the attack.