The author traces the history of the concept of schizophrenic psychoses from Kraepelin's differentiation of dementia praecox from other mental illness and Bleuler's formulation of schizophrenia through the delimitation of the definition of schizophrenia to current thought on the etiology, treatment, and outcome of schizophrenic psychoses. He stresses the importance of our knowledge of both psychological and hereditary factors and urges that rather than searching only for a single, causal metabolic error we also accept the possibility that schizophrenia occurs in highly human, spiritual spheres and consider the schizophrenogenic influences in the lives and personalities of individual patients.