Letter 123 — On the Conflict Between Pleasure and Virtue (§8)

“You should avoid conversation with all such persons: they are the sort that communicate and engraft their bad habits from one to another. We used to think that the very worst variety of these men were those who vaunted their words; but there are certain men who vaunt their wickedness. Their talk is very harmful; for even though it is not at once convincing, yet they leave the seeds of trouble in the soul, and the evil which is sure to spring into new strength follows us about even when we have parted from them.”