Claudius Galen
Galen (born 129 ce, Pergamum, Mysia, Anatolia [now Bergama, Turkey]—died c. 216) was a Greek physician, writer, and philosopher who exercised a dominant influence on medical theory.He distinguished seven pairs of cranial nerves, described the valves of the heart, and observed the structural differences between arteries and veins. One of his most important demonstrations was that the arteries carry blood, not air, as had been taught for 400 years. Notable also were his vivisection experiments.-PKK