This paper describes psychoanalysis as a theory and practice aimed at the attainment of truth. In this sense, it resembles other fields of science, and its traditions are paradigms that have been formed through the accumulation of clinical evidence, and which in turn shape what we can see. But psychoanalysis is specifically concerned with the truth of psychic reality and with change that occurs through coming to know this truth and withstand it, and thus tradition in psychoanalysis also refers to the boundaries of the field defined by this concern. By tracing some of the developments of psychoanalytic thinking from Freud through Klein and Bion, the paper stresses how these analysts have introduced significant changes in psychoanalysis both in terms of content and method, while still adhering to its essential tradition of a search for truth.