[Vesalius and De humani corporis fabrica: Galen's errors and the change of anatomy in the sixteenth century].

In medieval universities, human dissections were in general unusual, and public dissections were moreover strictly standardized. At public anatomical lessons three persons were needed to perform an autopsy. The Lector (a lecturer) read and commented on an authoritative text, which usually was Mondino dei Liuzzi's Anatomy. The Ostensor pointed out to the sector, normally a surgeon or a barber, the part of the body to be dissected. The procedure followed the text, the truth of which was not, questioned, and what was seen in a dissected body only confirmed what was stated in the text. In his De Humani corporis fabrica Vesalius criticized both the medieval method of dissection and the dependence of anatomy on authoritative texts. Vesalius wanted to unite the roles of lector, ostensor and sector. In Vesalius's view, a lecturer on anatomy must be able to dissect a cadaver himself and trust his own eyes more than authoritative text. Relying on his own eyes Vesalius gradually began to doubt the truth of various anatomical statements found in Galen's anatomical treatises. Galen (ca. 130-200) was the greatest medical authority during the Renaissance, and he was regarded as almost infallible. In Galen's person culminated the idealism of Renaissance humanism, according to which medical truth rested solely on ancient, especially Greek, heritage. The primary task of the medical humanist was to return to the ideas of the ancients. Vesalius's attitude toward this idealism was somewhat ambiguous. On one hand he found antique evidence for the view that anatomy should be based on one's own experience achieved by dissection of human cadavers. On the other hand he was forced to question the infallibility of Galen. Vesalius solved the discrepancy between the proof of his own eyes and the humanistic ideal by pointing out that anatomy had occupied a much higher level before Galen, in ancient Alexandria, and that Galen in his anatomical works had relied too much on animal dissection....