Which C.S. Lewis work presents letters from a senior demon advising a junior tempter?

The Screwtape Letters presents letters from a senior demon advising a junior tempter. C.S. Lewis published the book in 1942, using the correspondence between Screwtape and his nephew Wormwood to satirize temptation and self-deception.

The letters are written from a deliberately inverted viewpoint: the demons describe moral failure as success and virtue as a threat. Lewis uses this device to examine ordinary habits such as distraction, vanity, resentment, and rationalization rather than focusing only on dramatic wrongdoing.

The book began as a series of pieces in the Anglican newspaper The Guardian before appearing in book form. Its epistolary structure makes it different from Lewis’s fictional chronology of Narnia and from his direct apologetic works. Although the demons are fictional speakers, the book’s observations are intended as Christian moral and psychological commentary.