In The Screwtape Letters, C.S. Lewis provides a series of lessons in the importance of taking a deliberate role in living out Christian faith by portraying a typical human life, with all its temptations and failings, as seen from devils' viewpoints. Screwtape holds an administrative post in the bureaucracy ("Lowerarchy") of Hell, and acts as a mentor to Wormwood, the inexperienced tempter. In the body of the thirty-one letters which make up the book, Screwtape gives Wormwood detailed advice on various methods of undermining faith and promoting sin in the Patient, interspersed with observations on human nature and Christian doctrine. Wormwood and Screwtape live in a peculiarly morally reversed world, where individual benefit and greed are seen as the greatest good, and neither demon is capable of comprehending or acknowledging true human virtue when he saw it.