Along with The Chronicles of Narnia and Mere Christianity, C. S. Lewis' best known and most often read book is The Screwtape Letters. In it, Lewis allows readers to eavesdrop on the infernal correspondence between a senior devil named Screwtape and his nephew Wormwood. As Screwtape instructs his naive pupil in the fine art of temptation, he helps him to see that humans are best snared not through a grand tragic sin, but through a series of little sins that slowly draw them away from God, from reason, from joy and from their own humanity.