The plan of this thesis is to examine the dramatic treatment of evil as deception or false appearance in a representative selection of fourteenth- and fifteenth-century morality plays. The structural core of these plays Is based on the Psychomachia, or conflict between good and evil in man’s soul, which forms the dominant theme of Medieval allegory. In the morality plays, this conflict Is most characteristically presented as a plot of deception In which Vice masquerading as Virtue tempts Mankind by sophistical argument into believing that evil is good. Theologically, this theatrical metaphor of disguise is rooted in the Medieval concept of Satan as the arch-deceiver and father of lies who can take many Protean shapes in his efforts to ensna...