In the apparatus of the psyche, the Thing represents the secret center of human desire, the nucleus of pleasure/unpleasure. This nucleus is opposed to the reality principle, which it threatens to undermine. The Thing, also called the "lost object," acts as the cause of desire and a sign of longing for an impossible reunion with the object.
Sigmund Freud first referred to the Thing in 1895, in "A Project for a Scientific Psychology" (1950a). He used the term again in 1925 in his essay "Negation." Jacques Lacan fully elaborated this Freudian notion in his seminar The Ethics of Psychoanalysis (1992).
An instance of the Thing develops from a complex set of cathected perceptions and memory images that have given pleasure in the past. This set includes a stable kernel, called the Thing, and a variable element, or predicate. The Thing arises in the primordial relation between the infant seeking fulfillment of its vital needs and the primary caregiver, the "fellow being," who is also the first hostile object. The kernel or nucleus is inaccessible to judgment, while the predicate is the object of a judgment that must verify whether the memory image corresponds to reality. In Lacanian psychoanalysis, this process of judging forms the basis for the ego.
The Thing is situated in the unconscious articulation of desire. In its origin, it posits the Other as unconscious, as the force withholding the signifier of satisfaction, while reality is subverted by the symbolic function of memory traces of the lost object, from which the subject's desire is alienated.
See also: "Negation"; Other, the; Subject's desire; Unary trait.
Freud, Sigmund. (1925h). Negation. SE, 19: 233-239.
——. (1950c ). A project for a scientific psychology. SE, 1: 281-387.