Speusippus c. 408 BC – c. 339 BC

Speusippus was a Greek philosopher of Athens, the nephew of Plato, and his successor as scholarch of the Academy from 347 BC to his death in 339 BC. He broke with Plato on the theory of Forms and developed an independent metaphysics in which the first principle is the One and a separate principle of multiplicity, with mathematical entities and soul forming the intermediate levels of reality. His large body of writings, treating mathematics, biology, and ethics, was much used in antiquity but survives only in later citations and the testimony of Aristotle. He is the first known Greek philosopher to identify the good with happiness rather than with the One.