The book begins with a brief explanation from C.S. Lewis, the author. Lewis insists that he will not explain how he came to “find” the material that makes up the book. He argues that there are two ways to be influenced by devils: don’t believe in them, or believe in them and admire them.
In his preface, Lewis sets the tone for the novel: while it’s a work of fantasy, and an amusing one at that, it has serious Christian and moral overtones that can’t be ignored.
Lewis goes on to remind the reader that the devils in his book shouldn’t be trusted. Screwtape (a character who hasn’t yet been introduced) distorts the truth and portrays certain characters inaccurately.
While it might seem obvious that we shouldn’t trust devils, Lewis wants to distinguish his work from other notable texts about Satan and the underworld. Most notable among these might be John Milton’s Paradise Lost, which is explicitly mentioned later in the text. While Milton arguably leaves it unclear whether or not we’re meant to sympathize with his Satan character, Lewis wants to make it crystal clear that Screwtape is meant to be distrusted.
Lewis explains when the book is “set.” Although several letters refer to the events of World War II, Screwtape clearly isn’t interested in human history. His letters are dated, but their dates have little to do with human conceptions of time.
Paradoxically, this offhanded explanation of the novel’s setting actually encourages us to apply its moral teachings to the present day. Because the novel takes place during World War II, Lewis’s original readers can more easily compare it to their own experiences, while at the same time Lewis makes it clear that one can understand his book outside the context of war—it’s a text for “all time.”