In this chapter, the author aims to expand on some ideas that he developed in 1993 for a conference on the meaning of Jewishness in S. Freud's work, and to widen the field that he took into consideration at that time—the work of the creator of psychoanalysis—so as to cover the entire discipline. He then considers the concept of "zone of proximal development". Returning to the role of the preconscious, the author emphasizes that at a cognitive level this area of mixture and transition, of conceptual "negotiation", has affinities with the role that Sandler, working on the two censorships and on the "three-box model", attributed to the preconscious. Psychoanalytic concepts, learned and official, must continually come to grips with the derivatives of the unconscious, with what is activated in the unconscious in clinical practice and forces the concepts to a constant work of evolution and re-elaboration.