DIDYMUS of Alexandria, an ecclesiastical writer, born in 309 or 314. Although he became blind at the age of four, before he had learned to read, he succeeded in mastering the whole circle of the sciences then known: and on entering the service of the church he was placed at the head of the Alexandrian theological school. He died in 394 or 399. Most of his theological works are lost. We possess, however, a Latin translation by Jerome, who was one of his pupils, of his Treatise on the Holy Ghost (Liber de Spiritu Sancto), and a similar translation by Epiphan ius of bis Brief Comments on the Canonical Epistles (Breves Enarrationes in Epistolas Canonicas). A Treatise against the Manichaeans (Liber adversus Manichaeos) is extant in the original Greek, and was first published at Bologna in 1769.