Based on sophisticated clinical descriptions and characteristic symptom patters occurring during the long-term course of psychiatric diseases, Leonhards classification requires that all the clinical features fit for a diagnosis to be made. Always using his own life-long case studies, Leonhard divided the endogenous psychoses into five main nosological groups: on the one hand, the prognostically favourable unipolar affective psychoses, bipolar affective psychoses and cycloid psychoses, and, on the other hand, the prognostically unfavourable unsystematic and systematic schizophrenia. In the...