Scientists, clinicians, philosophers, and historians have long preened themselves on the modern scientific method through which, in large part, arose the great advances of the post-Renaissance world. Ancient and medieval physicians, on the other hand, have been widely criticized for their dependence on authority, uncritical acceptance of tradition, and failure to see for themselves. Quite unfairly the arch sinner in this regard has sometimes been considered to be Galen, who exerted canonical authority in medicine for about 1,500 years. His word was considered law, his pronouncements, the ultimate authority. It was not, of course, Galen's fault that 40 subsequent generations regarded him as the fountainhead of wisdom. Nevertheless, he has been unjustly blamed because his followers lacked the true scientific method.
According to popular belief, Vesalius was the great Renaissance figure who insisted on observing for himself and thereby overthrew the Galenic errors. Vesalius himself, of course, was not always