The Cambridge Companion to Galen - Paperbackby R. J. Hankinson (Editor) Galen of Pergamum (AD 129 c. 216) was the most influential doctor of later antiquity, whose work was to influence medical theory and practice for more than fifteen hundred years. He was a prolific writer on anatomy, physiology, diagnosis and prognosis, pulse doctrine, pharmacology, therapeutics, and the theory of medicine; but he also wrote extensively on philosophical topics, making original contributions to logic and the