"I myself visited this same Abba Kosmas when he was in the Lavra of Pharan, and I stayed there for twelve years. He was talking to me once for my soul's health and mentioned something from the sayings of holy Athanasius, Archbishop of Alexandria.
'If you come across something from the works of Athanasius,' he said, 'and you haven't got any paper with you to write it down on, write it on your clothing.' This was typical of how great was the zeal which this old man had for our holy fathers and teachers."
- John Moschos, The Spiritual Meadow, Ch. 40
"Read the same holy man's Against Arius and his Doctrines, in five books. The style, as in all his works, is clear, free from redundancies and simple, but vehement and deep, and the arguments, of which he has an abundant store, are extremely forceful. He uses logical arguments, not with the very words taken straight from them, after the fashion of children and those whose knowledge of a subject is recent, who are always eager to make a childish display, but in the imposing and dignified manner of a philosopher, using simple ideas and these well set forth. He also strongly fortifies himself with evidence and proofs from Holy Writ. In a word, this work alone is a complete refutation of Arianism. If any one were to say that Gregory the Theologian and the holy Basil drew from it as from a fountain the limpid and beautiful stream of their own works written against the same heresy, he would not be far wrong."
- Photios the Great, Myriobiblon 140
"He speaks plainly, he is intelligent, sensible and conscientious, in a word he is ideally qualified to be a teacher. He has none of the heaviness that offends in Tertullian; there is nothing flashy as in Jerome; nothing labored as in Hilary; nothing redundant as there is in Augustine and even in Chrysostom; nothing that smacks of the cadences of Isocrates or the studied artistry of Lysias such as one finds in Gregory of Nazianzus. Instead he concentrates wholly on making his meaning clear."
- Erasmus, Letter 1790, March 3, 1527
"Photios observes, that the diction and style of St. Athanasius is clear, majestic, full of deep sense, strength, and solid reasoning, without any thing redundant or superfluous. He seems to hold the next place in eloquence after St. Basil, St. Gregory Nazianzen, and St. Chrysostom. Erasmus even admires his style above that of all the other fathers, saying, it hath nothing rugged or difficult, like that of Tertullian, nothing laboured or embarrassed, like that of St. Hilary, nothing studied, like that of St. Gregory Nazianzen; no windings and turnings, like that of St. Augustine, or of St. Chrysostom: for it is everywhere beautiful, elegant, easy, florid, and admirably adapted to whatever subject he treats: though in some of his works it wants the finishings which more leisure would have given it. Kosmas, an ancient monk, used to say, 'When you find any thing of the works of St. Athanasius, if you have no paper, write it on your clothes.'"
- Rev. Alban Butler, Lives of Saints, May 2