O.k., I begin to suspect that I was conflating two different passages in my fading memory, one by Augustine and the other by C. S. Lewis.

"Let him do anything but act. No amount of piety in his imagination and affections will harm us if we can keep it out of his will. As one of the humans has said, active habits are strengthened by repetition but passive ones are weakened. The more often he feels without acting, the less he will be able ever to act, and, in the long run, the less he will be able to feel."
- C. S. Lewis, The Screwtape Letters, Letter 13

"If, when a thief stole money, he lost an eye, everybody would say that it was a punishment of God. Yet; you have lost the eye of your mind and you think that God has not punished you."
- Saint Augustine, In Ps. 47

Lewis is quoting Joseph Butler's The Analogy of Religion, but the passage does seem to have an echo of what Augustine said.

Valentius, you were so helpful last time around, I think I'll bother you with another Augustine quote from W. H. Auden's The Dyer's Hand. Auden quotes Augustine as saying (I paraphrase) that if we know the good and do not do it, soon we will cease to know the difference between good and evil.

I don't trust my paraphrase of Auden's paraphrase, so I'd like to identify the original quotation (Auden has no footnotes). Does that ring a bell at all? Any idea where I might find that in Augustine's works?

Thank you! That makes perfect sense. Do you happen to know if Augustine used this particular terminology? Did he ever explore the explicit dichotomy of society VS community? If he did so in the City of God, where in the City of God did he do so?

Thanks again for this response. I didn't get a notification of a response and only just now saw it.