Galen (130-200 AD), Greek physician. After Galen's death, his body of work became a medical authority among Europeans, until his views on anatomy were overthrown by Vesalius (16th century) and those on physiology by Harvey (17th century). In Galen's time, human dissection had fallen into disrepute, and Galen's anatomical assumptions, which were based on animals, were not, as it was later seen, always applicable to humans. He was the first to use the pulse as a diagnostic aid and the first to describe the flow of urine through the ureters to the bladder. Artwork from an unnamed book by the 16th century French surgeon Ambroise Pare.