Ekstein's book brings together papers on a number of themes which have occupied his thinking during the last 40 years. In the Wiener Kreis, the Vienna circle of philosophers, he studied, together with his professor Moritz Schlick, the philosophy of science, the analysis of language, and the clarification of meaning. Throughout his life he has always been inspired by the work of Ludwig Wittgenstein. In the Vienna Psychoanalytic Institute his interest in psychotherapy and psychoanalysis was reinforced, and he established for himself a bridge between the kind of thinking that looks for philosophical clarification and that which searches for psychological meaning. The psychotherapeutic and psychoanalytic methods of psychological clarification depend on the language tools of the thinking process. But these language tools, referring now to different theories of psychoanalysis and psychotherapy in the various schools, have their usefulness as well as their limitations. Ekstein's chronological assessment allows us to arrive at a philosophical and psychological clarification of present psycho-therapeutic and psychoanalytic schools.