Lewis: Temptation and Sin

C. S. Lewis, letter to Mary Neylan, January 20, 1942:

I know all about the despair of overcoming chronic temptations.

It is not serious provided self-offended petulance, annoyance at breaking records, impatience etc doesn't get the upper hand. No amount of falls will really undo us if we keep on picking ourselves up each time. We shall of course be very muddy and tattered children by the time we reach home. But the bathrooms are all ready, the towels put out, and the clean clothes are airing in the cupboard.

The only fatal thing is to lose one's temper and give it up. It is when we notice the dirt that God is most present to us: it is the very sign of His presence.

--The Collected Letters of C. S. Lewis, Volume 2 (Cambridge University Press, 2004), 507; emphasis original