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
Ptolemy II Philadelphus in the Library of Alexandria to the Capodimonte Palace by Gioacchino Murat and then in 1867 moved to the Palazzo Reale di Napoli, before being given to the Camera dei deputati in Palazzo Montecitorio in Rome. It later returned to Naples and since 1997 has hung in its original position in Room 31 of the Royal Apartments, also known as the Salone della Culla. Ptolemy II Philadelphus in the Library of Alexandria Ptolemy Philadelphus in the Library of Alexandria is an 1813 oil on canvas painting by Vincenzo Camuccini. It is now in the National Museum of Capodimonte in Naples. The work was commissioned by