Bp. of Alexandria from 248. He fled from the city in the Decian persecution (250) and was banished in that of Valerian (257). He took part in various important controversies. He decided to readmit to the Church those who had lapsed under persecution and, with Pope Stephen, not to rebaptize heretics and schismatics. He attacked Sabellianism but was accused of tritheism by Dionysius (5) of Rome, who accepted his defence. Feast day, 17 Nov.