It is relatively common in fantasy literature to give power to names. The concept, drawn from folklore, is based on the notion of true names, whereby a person's true name is a powerful magical weapon against them; this seldom applies to objects. In works from Larry Niven's The Magic Goes Away to Andre Norton's Witch World, wizards and witches keep their names secret to keep from their being used against them. In the Discworld books by Terry Pratchett, the Librarian hides his name to keep from being turned back to a man. This concept was also used in the Doctor Who episode The Shakespeare Code.