The Emperor's New Clothes

"The Emperor's New Clothes" is a short tale by Hans Christian Andersen, about two con-men weavers who tell an emperor they can make him a new suit of clothes that is invisible to people who are unfit for their positions, stupid, or incompetent. Parading before his subjects in his new "clothes", no one is willing to admit to themselves or others that the emperor is essentially naked. When a child cries out, "But he isn't wearing anything at all!" the crowd repeats the cry and the Emperor continues parading. As an idiom, the story's title refers to things that are accepted as common knowledge in spite of being obviously untrue.