Here are 5 things I learned reading, The Screwtape Letters, By: C.S. Lewis (Amazon).
1. Prosperity ties you to this world.
2. Death is not the worst evil. And life is not the supreme good.
3. Stay away from nearly all extremes.
4. Suspense and anxiety are your enemy.
5. “There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them. They themselves are equally pleased by both errors and hail a materialist or a magician with the same delight.”