[Birth and vicissitudes of the mental disease concept]

The author discusses the successive modifications of the concept of mental disease. Initially syndromic, it has tended, since Bayle, to become clinico-etiological. The introduction of evolution as a criterion is responsible for the "Krankheitsbegriff" of Kraepelin. The initially categorical nature of the model has met with difficulties when personality disorders has been considered as belonging to psychiatry. Kurt Schneider has tried to solve the problem thus posed. Although it is avoided by the modern nosological systems, the choice between the categorical and the dimensional models is a prerequisite for a clear definition of mental disease.