Erasistratus of Chios (330? BC - 250? BC) was a Greek anatomist. He worked as royal physician under Seleucus I Nicator and founded a school of anatomy in Alexandria along with Herophilos. He regarded atoms as the essential body elements, and they were vitalized by external air (pneuma) circulating through the arteries. He thought that the nerves moved a "nervous spirit" from the brain, from which Erasistratus traced sensory and motor nerves. He also believed that the arteries moced an "animal spirit" from the heart by air provided by the lungs. He is best known for curing Antiochos, Seleucus's son. Erasistratus said that Antiochos was in love with his stepmother, and that that was what was ailing him, so he let them marry.