We must beware of the Past, mustn’t we? I mean that any fixing of the mind on old evils beyond what is absolutely necessary for repenting our own sins and forgiving those of others is certainly useless and usually bad for us. Notice in Dante that the lost souls are entirely concerned with their past. Not so the saved. This is one of the dangers of being, like you and me, old. There’s so much past, now, isn’t there? And so little else. But we must try very hard not to keep on endlessly chewing the cud. We must look forward more eagerly to sloughing that old skin off forever—metaphors getting a bit mixed here, but you know what I mean.
—The Collected Letters of C.S. Lewis, Volume III (via zerogate)