Alcmaeon of Croton c. 540 BC – c. 460 BC

Alcmaeon of Croton was a Greek pre-Socratic philosopher and physician, sometimes counted among the early Pythagoreans of southern Italy. He is the earliest known author of a Greek work on natural philosophy concerned with medicine, of which only short fragments survive, and is credited by ancient sources with the first anatomical investigations by dissection in the Greek tradition. His most consequential thesis is that the brain, not the heart, is the seat of sensation and thought, a doctrine that shaped Hippocratic medicine and entered the wider Greek philosophical inheritance through Plato. He also defined health as the harmony of opposed powers.