Theon of Alexandria Theon of Alexandria Theon of Alexandria (; ; 335 – c. 405) was a Greek scholar and mathematician who lived in Alexandria, Egypt. He edited and arranged Euclid's "Elements" and wrote commentaries on works by Euclid and Ptolemy. His daughter Hypatia also won fame as a mathematician. Little is known about the life of Theon. He made predictions and observances of solar and lunar eclipses in 364 which show he was active at that time, and he is said to have lived during the reign of Theodosius I (379–395). The biographical tradition of the tenth century Byzantine "Suda" defines Theon
Library of Alexandria scrolls in its collection, so, during the reign of Ptolemy III Euergetes, it opened a satellite collection in the Serapeum of Alexandria, a temple to the Greco-Egyptian god Serapis located near the royal palace. Aristophanes of Byzantium (lived 257– 180 BC) became the fourth head librarian sometime around 200 BC. According to a legend recorded by the Roman writer Vitruvius, Aristophanes was one of seven judges appointed for a poetry competition hosted by Ptolemy III Euergetes. All six of the other judges favored one competitor, but Aristophanes favored the one whom the audience had liked the least. Aristophanes declared that