Galen

Galen of Pergamon was physician to gladiators and then to Marcus Aurelius, and the most prolific author of antiquity, some three million words on anatomy, physiology, pharmacology, logic and his own excellence. He dissected apes and pigs, since human dissection was forbidden, proved that arteries carry blood, and built a system on the four humours and three spirits that ruled medicine until Vesalius and Harvey overthrew it fourteen centuries later. On the Natural Faculties argues that the body’s powers of attraction, retention and expulsion cannot be explained by atoms and mechanism. Al-Razi’s Doubts is the first systematic criticism.