At that period at Edessa flourished the admirable Ephraim, and at Alexandria Didymus, both writers against the doctrines that are at variance with the truth. Ephraim, employing the Syrian language, shed beams of spiritual grace. Totally untainted as he was by heathen education he was able to expose the niceties of heathen error, and lay bare the weakness of all heretical artifices. Harmonius the son of Bardesanes had once composed certain songs and by mixing sweetness of melody with his impiety beguiled the hearers, and led them to their destruction. Ephraim adopted the music of the songs, but set them to piety, and so gave the hearers at once great delight and a healing medicine. These songs are still used to enliven the festivals of our victorious martyrs.
Didymus, however, who from a child had been deprived of the sense of sight, had been educated in poetry, rhetoric, arithmetic, geometry, astronomy, the logic of Aristotle, and the eloquence of Plato. Instruction in all these subjects he received by the sense of hearing alone, -- not indeed as conveying the truth, but as likely to be weapons for the truth against falsehood. Of holy scriptures he learnt not only the sound but the sense. So among livers of ascetic lives and students of virtue, these men at that time were conspicuous.