Besieged by devils--thoughts on possession and possession states.

Aspects of possession are reviewed in historical, cultural and clinical contexts. Consideration is given to differential diagnosis and management. It is suggested that a multi-disciplinary approach is required for a condition that stands at the boundaries of psychiatry. Two quotations from Elizabethan playwrights are relevant to the theme of this paper: 'Beware you do not conjure up a spirit you cannot lay' Ben Johnson, The New Inn (Act III, Scene ii) 'Farewell the tranquil mind: farewell content.' Shakespeare, Othello (Act III, Scene iii).