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

Social responsiblity is a recurring idea in the narrative. Most notably, "Why I am not a Pacifist" expresses Lewis's carefully developed views about one's responsibility within society. In the conclusion of this sermon, Lewis points out that someone's willingness to fight in the past reserves one's right now to express pacifist views. Though he admits that war is not an ideal, it exists as a necessary evil.