I wish to stress the fact that it has always been the differentiation of aetiologically different psychiatric syndromes, that has made useful psychiatric classification possible by providing clear description of inherent characteristics. However, as there are several psychiatric disorders the causes of which are still unknown, clinical experience calls urgently for a classification of psychiatric groups that have several common traits in respect to symptomatology, course and treatment. Such a systematization might be of great significance to research into prognostication and treatment of the individual case. As team work from our clinic(6) has shown, it is possible even in the initial stage of a case of schizophrenia to predict the course with a certainty of more than 90%. In addition it is also possible in the initial stage to indicate which of the modern treatments has the best chance of success. Consequently if the significance of the dichotomy in psychiatry were generally accepted it would probably mean a great advantage in international comparative psychiatry.Abstract Teaser