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 I of Tusculum (temporarily) resumed. Ptolemy and his nephew the prefect were holding the Castel Sant'Angelo. Peter Colonna and Rainald Senebaldi turned to the pope's side and, soon after Christmas, Ptolemy and the rest of the imperialists in the Eternal City were forced to flee by the pope, who soon died. Ptolemy I of Tusculum Ptolemy I ( or ; died 1126) was the count of Tusculum in the first quarter of the twelfth century. He was a son of Gregory III. Peter Pisanus, in his "Vita Paschalis II" refers to Ptolemy and the abbot of Farfa as the allies of the emperor