Simplicius of Cilicia

Simplicius of Cilicia was a Greek scholar of the sixth century, born in Cilicia in southern Anatolia, who is remembered as a commentator on the works of earlier philosophers and mathematicians, above all Aristotle and Euclid. He studied philosophy in Alexandria under Ammonius Hermiae and then in Athens under the Neoplatonist Damascius. When the emperor Justinian closed the pagan schools in 529, Simplicius, Damascius and five colleagues left for the court of the Persian king Khosrow I, and a peace treaty ratified in 532 allowed them to return. His surviving works are carefully built interpretations rather than lecture notes, and they try to harmonise the views of Plato and Aristotle. His commentaries on Aristotle's On the Heavens and Physics matter greatly to the history of mathematics, because they quote at length from lost works such as Eudemus's History of Geometry and History of Astronomy, preserving accounts of Antiphon's attempts to square the circle, the lunes squared by Hippocrates, and the concentric spheres of Eudoxus with Callippus's modifications. His commentary on Euclid's Elements survives in Arabic translation, and his attempted proof of the parallel postulate entered Arabic mathematics, where it was criticised and then reworked.