Saint Basil the Great, (born ad 329, Caesarea Mazaca, Cappadocia—died Jan. 1, 379, Caesarea; Western feast day January 2; Eastern feast day January 1), Early church father. Born into a Christian family in Cappadocia, he studied at Caesarea, Constantinople, and Athens and later established a monastic settlement on the family estate at Annesi. He opposed Arianism, which was supported by the emperor Valens and his own bishop Dianius, and organized resistance to it after 365. He succeeded Eusebius as bishop of Caesarea in 370. He died shortly after Valens, whose death in battle opened the way for the victory of Basil’s cause. More than 300 of his letters survive; several of his Canonical Epistles have become part of canon law in Eastern Orthodoxy.