What metaphors are used in The Weight of Glory and Other Addresses by C. S. Lewis?

In the section, On Forgiveness, Lewis tells the listener that excuses, rarely useful in real life, also get nowhere with God. He has heard them all before. Here Lewis uses a doctor's visit as a metaphor. If a patient suffers from a broken arm, explaining to the doctor that every other body part is OK is a waste of precious time. Ultimately, man's excuses stem from some element of unbelief. Man feels God will not accept him without an excuse.