Everything you need to understand or teach The Ninth Configuration by William Peter Blatty.
Besides being antimilitary and asking how madness is defined, the novel explores the problematic nature of identity—in keeping with both the 1960s "identity crises" and the later spread of psychotherapy and self-help books. Literally, the whole plot depends on an identity confusion, hinted at in mysterylike fashion throughout the book, and a deliberate masquerade, revealed more suddenly towards the end. The first scene features an inmate presenting himself as Dr. Fell...