Plato also speculated that the brain was the seat of the rational part of the soul.[1] Aristotle, however, believed the heart was the center of intelligence and that the brain regulated the amount of heat from the heart.[2] This view was generally accepted until the Roman physician Galen, a follower of Hippocrates and physician to Roman gladiators, observed that his patients lost their mental faculties when they had sustained damage to their brains.