4. Of Alexandria, lived in the fourth century of the Christian era, and must be distinguished from Didymus the monk, who is spoken of by Socrates. (Hist. Eccles. 4.33.) At the age of four years, and before he had learnt to read, he became blind; but this calamity created in him an invincible thirst after knowledge, and by intense application he succeeded in becoming not only a distinguished grammarian, rhetorician, dialectician, mathematician, musician, astronomer, and philosopher (Socrat. 4.25; Sozom. 3.15; Rufin. 11.7; Theodoret. 4.29; Nicephor. 9.17), but also in acquiring a most extensive knowledge of sacred literature. He devoted himself to the service of the church, and was no less distinguished for the exemplary purity of his conduct than for his learning and acquirements. In A. D. 392, when Hieronymus wrote his work on illustrious ecclesiastical authors, Didymns was still alive, and professor of theology at Alexandria. He died in A. D. 396 at the age of eighty-five. As professor of theology he was at the head of the school of the Catechumeni, and the most distinguished personages of that period, such as Hieronymus, Rufinus, Palladius, Ambrosius, Evagrius, and Isidorus, are mentioned among his pupils.
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890