Kraepelin's formulation of dementia praecox is reviewed, with the irrelevant and misleading ontological conception of disease, dissected away, to restore his fruitful emphasis on a characteristic tendency toward developmental arrest and regression that produces the picture of deterioration, ie, "dementia." Bleuler's valuable contributions of a biographic approach and wide nosological expansion to include virtually all the functional psychoses are considered. His attempt to apply a psychoanalytic interpretation based principally on symptom analysis and associationism, in the schizophrenia concept, is rejected as premature. A psychoanalytic, characteriological approach along developmental lines that can be integrated with Kraepelin's original formulation is now possible in view of advances in psychoanalytic observation and theory over the past 60 years.