How we cite our quotes: (Book.Section.Paragraph)
Quote #10
By your grace it will no longer commit in sleep these shameful, unclean acts inspired by sensual images, which lead to the pollution of the body: it will not so much as consent to them. (X.30.2)
To live a chaste life is one thing. But how are you supposed to avoid having unchaste dreams? Answer: by the grace of God, of course. While this might not sound like a very satisfying (ahem) answer, Augustine is getting at the idea that human will is pretty weak. So weak, in fact, that even when we resolve to not give into lust, our brains keep on lusting while we're asleep. So if you can't trust your own brain, you have to trust in God.