The roots of the anthropo-phenomenological approach in psychiatry, of that trend which found its ripest expression and — above all — its methodology in Binswanger's Daseinsanalyse, can be traced back to an ancient problem: the determination by psychology, and later by psychopathology, of what arguments are pertinent to its particular plane of research. In their attempts to arrive at a solution, psychologists have been driven to adopt ambiguous physiological viewpoints at one pole, and ingenuous philosophical theorizations at the other. This happened because classical psychology and psychopathology did, in fact, treat of an object that was at the same time a subject — namely the Ego, and any theory that reduces the Ego to an object denatures it fatally, while whatever theory preserves it as a subject cannot be fitted into the scheme of natural science.