DIONYSIUS OF ALEXANDRIA (c. bishop of Alexandria, called "Dionysius the Great," became a Christian when young and studied under Origen. In 231 he was made head of the Catechetical school of Alexandria, and in 247 bishop of that city. During the Decian persecution in 251 he fled to the Libyan desert, while under Valerian he was banished to Cephro in 257, returning when toleration was decreed by Gallienus in 26o. He was engaged in controversy over the restoration of Christians who had lapsed during the persecution, and over the iteration of baptism by heretics. In opposing the bishops of Upper Libya who supported Sabellianism, Dionysius overem phasized the unity of the Godhead. He had to express his ortho doxy in Refutation and Defence. Eusebius in Hist. Eccl. often cites him, and in Praep. Evang. xiv. quotes some fragments of the On Nature. The fragments were edited by Simon De Magistris, S. Diony. Alex. Opera Omnia (Rome, 1796), by Migne, Pat. Graeca, x., and C. L. Feltoe, Letters and other Remains of Dionysius of Alexandria (Cambridge, 1904 ; Eng. trans. 1918) . See also Dittrich, Dionysius der Grosse (Freeburg i. B., 1867) and J. Burel, Denys d'Alexandrie (191o).