In this article das Ding is characterized as the structural a priori condition for memory and, more broadly, for the subject in its desire. First, the fundamentally conflicting nature of the psychical apparatus as outlined by Freud in his Project for a scientific psychology (1950a[1895]) is examined. The elaboration of the opposition between the primary processes or the pleasure principle on the one hand and the secondary processes or the reality principle on the other is of crucial importance. The ambiguity that characterizes this opposition is related to the Freudian notion of das Ding as the residue of the process of judgement through which a subject tries to grasp the outside world and the Nebenmensch. Das Ding, as the primordial outside of the subject, is then characterized, with Lacan, as the centre around which the subjective world of the unconscious is organised but from which it is nevertheless excluded. Finally, the implications of this theory for the desiring subject on the one hand and for an articulation of the ethics of psychoanalysis on the other are addressed.