In this lively, penetrating book, Michael Williams challenges the validity of the widely invoked category of ancient "gnosticism" and the ways it has been described. Presenting such famous writings and movements as the Apocryphon of John, Valentinian Christianity, and other sources, Williams uncovers the similarities and differences among some major traditions widely categorized as gnostic. Moreover, he provides an eloquent, systematic argument for a more accurate way to discuss these interpretive approaches.