Originally, Kraepelin’s dementia praecox and Bleuler’s schizophrenias described heterogeneous psychoses with no restitutio in integrum. They were unbiased against deficit symptoms. The Wernicke-Kleist-Leonhard school sustained this heuristic notion of the schizophrenias. It rejected nosological hybridism, empirically separating developmentally more conspicuous systematic schizophrenias of insidious onset or course from genetically higher loaded unsystematic schizophrenias inclined to some bipolarity (i.e., periodic catatonia, affective paraphrenia, and cataphasia). Thus, periodic catatonia is but one of three unsystematic schizophrenias that were previously omitted from mention (2). Some well-described conditions dominated by specific deficits were grouped into hebephrenias, which exist only in systematic forms. In fact, various cases of heboidophrenia (Kahlbaum), dementia simplex (Weygandt and Diem), schizoidia (Bleuler and Kretschmer), schizotypes (Rado), latent schizophrenia (Bleuler), and pseudoneurotic schizophrenia (Hoch and Polatin) corresponded clinically to Kleist and Leonhard’s hebephrenias. Moreover, Leonhard passionately differentiated early childhood catatonias from mental retardation. Dementia infantilis (Heller) and early infantile autism (Kanner) overlapped to some extent with Leonhard’s systematic childhood catatonias, whereas autistic psychopathy of childhood (Asperger) denoted a nonschizophrenic condition.