400?-347? B.C.

Greek astronomer and mathematician who wrote on astronomy, mathematics, geography, philosophy, and drafted laws for his native town. He attended some of Plato's lectures and established his own school, where he lectured on astronomy, theology, and meteorology. Only fragments of his writings survive. His lost books include On Velocities, which influenced the planetary theory of Aristotle, and Tour of the Earth, which was quoted heavily by later geographers.