Which C.S. Lewis book presents seven letters from a senior demon advising a younger tempter?

The Screwtape Letters presents correspondence from the senior demon Screwtape to a younger tempter named Wormwood.

Published in book form in 1942, the work uses satire to examine temptation, self-deception, pride, distraction, and spiritual complacency. Screwtape’s advice is deliberately written from a demonic perspective, so the reader must infer the moral lessons from counsel that is meant to corrupt the human patient.

The letters originally appeared in the Anglican newspaper The Guardian, which published them weekly in 1941. Lewis later collected them into a book, adding a preface that explains the difficulties of presenting demonic material without making evil seem attractive.

A common mistake is to treat Screwtape as the human protagonist. He is the senior tempter and correspondent, while Wormwood is the inexperienced junior demon receiving instructions. The unusual epistolary format lets Lewis turn abstract ethical ideas into sharp observations about ordinary habits and motives.