590–591 · Gregory the Great, The Book of Pastoral Rule (Regula pastoralis) 4
But since often, when preaching is abundantly poured forth in fitting ways, the mind of the speaker is elevated in itself by a hidden delight in self-display, great care is needed that he may gnaw himself with the laceration of fear, lest he who recalls the diseases of others to health by remedies should himself swell through neglect of his own health; lest in helping others he desert himself, lest in lifting up others he fall. For to some the greatness of their virtue has often been the occasion of their perdition; causing them, while inordinately secure in confidence of strength, to die unexpectedly through negligence. For virtue strives with vices; the mind flatters itself with a certain delight in it; and it comes to pass that the soul of a well-doer casts aside the fear of its circumspection, and rests secure in self-confidence; and to it, now torpid, the cunning seducer enumerates all things that it has done well, and exalts it in swelling thoughts as though superexcellent beyond all beside. Whence it is brought about, that before the eyes of the just judge the memory of virtue is a pitfall of the soul; because, in calling to mind what it has done well, while it lifts itself up in its own eyes, it falls before the author of humility.