Personality is the psychophysical totality of human individuals, somatic by its contents and conscious by form, biologic by its origin and social by development. It should not be conceived as an entity, self-contained and coming into being at the very moment of generation or birth. Although its major features form already towards the end of puberty definitively, personality continues developing for life, till the moment of death. Its evolution consists in a transformation of biological regularities—to which human as well as other beings generally submit—into historical determinants. Just so, a human being is growing up from the state of a mere organism, an individual of his species, to an individuality, a personality, i.e. to a social category. In normal individuals, this transformation is the result of a continuous adequate assimilation of physiologic and mental activities to environmental conditions and their influence. At the consecutive stages of life, the creative appropriation of social practical knowledge is achieved in the proper abundance of capacities for experience and action. The restricted dispositions to a normal intellectual—mnemic activity—which are so indicative of mental deficiency—interfere with the sociological implication of defectives in the family, the school, and society as full-fledged individuals.