But when at Alexandria the foul gloom of perfidy of a murky teacher was overspreading the peoples and the city, the Lord kindled Didymus, like a kind of lamp shining with divine light. Concerning his life and habits, since he is believed to have been granted, by the gift of God, for the glory of the Church, a few things, though in passing, nevertheless necessarily seem to us to be recorded. For he, in tender age, while as yet he was ignorant even of the first elements of letters, having been deprived of his eyes, was inflamed with a greater desire for the knowledge of the true light; nor did he suffer despair of obtaining what he longed for, when he had heard it written in the Gospel: 'What is impossible with men is possible with God' (Matthew 19; Mark 10; Luke 18).
Trusting therefore in this divine promise, he unceasingly besought the Lord—not that he might receive the sight of his bodily eyes, but the illumination of his heart. Yet he mingled with his prayers study and labor, and applied continuous and unbroken vigils, not to reading but to listening, so that what sight conferred on others, hearing might confer on him.
But when, after the labor of nightly study, sleep (as is wont to happen) had come upon those reading, Didymus, not reckoning that silence given for rest or leisure, like a clean animal ruminating the food it had taken, recalled it afresh, and what he had a little before learned from the reading of books, while others were running through them, he wove again in memory and mind, so that he seemed not so much to have heard what had been read as to have written it upon the pages of his mind. Thus in a short time, with God teaching, he came to so great an erudition and knowledge of things divine and human that he stood forth as a Doctor of the Ecclesiastical school, highly approved by Bishop Athanasius and by the other wise men of God in the Church:
but also in the other disciplines, whether of Dialectic, or of Geometry, or of Astronomy too, or of Arithmetic, he was so well-prepared that no philosopher ever, propounding something from these arts, was able to get the better of him or to corner him; but as soon as one heard his answers, he would believe him to be a master even of that discipline about which he had propounded the question. Some sayings of his—whether disputed in common, or his answers to those who propounded questions—were taken down by employing shorthand-writers; and these even now are held in great admiration.
Yet we who were in some part hearers of his living voice, and who have read those things written down by certain persons as he spoke, recognized a far greater grace and something divine—I know not what—sounding above a human voice, rather in those discourses which were uttered from his own mouth. Him too the blessed Antony, when, about to bear testimony to the faith of Athanasius against the Arians, he had come down from the Thebaid to Alexandria, consoled with magnificent words: 'Let nothing offend thee, O Didymus,' he said, 'that thou seemest deprived of carnal eyes. For thou lackest those eyes which mice and flies and lizards have. But rejoice, because thou hast eyes which the Angels have, and by which God is seen, through which a great light of knowledge is kindled for thee.'