ABSTRACT
This chapter begins by studying interpretation as the principal instrument used by all the major psychotherapeutic methods. It tries to determine the essential characteristics of interpretation in psychoanalysis. Freud asserted that the method discovered by Breuer—cathartic psychotherapy—and the psychoanalysis developed from it operated per via di levare, not per via di porre, as did the other methods. This idea appears in almost all the works, where there is an attempt to differentiate psychoanalysis from psychotherapy. Bibring's thinking opens up a path towards a specification, which enables us to approach our theme at last: the difference between materials and instruments of psychotherapy, basically following Knight. It is both a geometric and a Pythagorean difference, according to which what arises from the patient is called material, and the analyst operates on this material with his instruments.
