John Cassian, Conferences XI–XVII XI.4: Of Abbot Chæremon and his excuse about the teaching which we asked for

And so the blessed Archebius thought it best to take us first to Chæremon, because he was nearer to his monastery, and because he was more advanced than the other two in age: for he had passed the hundredth year of his life, vigorous only in spirit, but with his back bowed with age and constant prayer, so that, as if he were once more in his childhood he crawled with his hands hanging down and resting on the ground. Gazing then at one and the same time on this man’s wonderful face and on his walk (for though all his limbs had already failed and were dead yet he had lost none of the severity of his previous strictness) when we humbly asked for the word and doctrine, and declared that longing for spiritual instruction was the only reason for our coming, he sighed deeply and said: What doctrine can I teach you, I in whom the feebleness of age has relaxed my former strictness, as it has also destroyed my confidence in speaking? For how could I presume to teach what I do not do, or instruct another in what I know I now practise but feebly and coldly? Wherefore I do not allow any of the younger men to live with me now that I am of such an advanced age, lest the other’s strictness should be relaxed owing to my example. For the authority of a teacher will never be strong unless he fixes it in the heart of his hearer by the actual performance of his duty.