[Pierre Janet's views on the etiology, pathogenesis and therapy of dissociative and conversion disorders ("hysterias")].

Pierre Janet (1859-1947) is one of those more or less forgotten authors whose approach differed significantly from Freud's psychoanalysis. In the first part of this paper, Janet's conception of hysteria is discussed and his place in French psychiatry described. Different aspects of Janet's diathesis-stress-approach are presented (particularly his important pathogenic concept of fixed ideas) which refer not only to a conception of hysteria, but also to traumatic (stress) disorders and other psychological disturbances. The second part of the paper details the varieties of Janetian therapeutic treatments for these disorders: the 'liquidation' of fixed ideas by hypnosis and suggestion, confrontation techniques which resemble contemporary cognitive behavioural approaches, and special cognitive ("logagogic") interventions. Finally, we also discuss the various treatment strategies Janet proposes for dealing with symptoms, such as asthenic or depressive states, from his psycho-economic perspective.