To love is to risk not being loved in return. To hope is to risk pain, but risk must be taken because the greatest hazard in life is to risk nothing.

Claude Monet, La Promenade, 1875.

The lack of a coherent formulation of psychiatric disorders encouraged two camps to develop, one dividing the behaviors into many conditions and the other oVering a single disorder of the brain as the basis for many forms of psychiatric illness.

The single cause for psychiatric disorders was formulated when anatomic studies showed diverse forms of mental illness to be associated with thickening of the brain’s meninges, later seen as secondary to cerebral syphilis. The brain diseases took various forms, one dissolving into another, and arguments ensued as to the relevance of a single brain disorder (Einheitspsychose) or multiple disorders.

Of many attempts to develop a coherent nomenclature, Emil Kraepelin’s formulation of melancholia as an abnormal mood state was widely accepted. An active and agitated form of the illness was grouped with manias, and the periodicity of recurrences was highlighted. He recognized two forms of the psychoses – a progressive deteriorating illness of dementia praecox (Verblo¨dungsprocesse) and a nondeteriorating form of periodic illnesses (das periodische Irresein). The latter term was replaced in his next edition by das manisch-depressive Irresein which established a condition of manic-depressive illness. Melancholia was retained as a separate depressive syndrome that occurred in a perceived ‘‘involutional period.’’ In writings in the first half of the Twentieth Century it became the syndrome of involutional melancholia.