John Cassian, The Institutes XI.13: Of the ways in which vainglory attacks a monk

In the case also of beginners and of those who have as yet made but little progress either in powers of mind or in knowledge it usually puffs up their minds, either because of the quality of their voice because they can sing well, or because their bodies are emaciated, or because they are of a good figure, or because they have rich and noble kinsfolk, or because they have despised a military life and honours. Sometimes too it persuades a man that if he had remained in the world he would easily have obtained honours and riches, which perhaps could not possibly have been secured, and inflates him with a vain hope of uncertain things; and in the case of those things which he never possessed, puffs him up with pride and vanity, as if he were one who had despised them.