In psychoanalysis, a defence mechanism, first identified in 1956 by the French psychoanalyst Jacques Lacan (1901–81), involving the expulsion of a fundamental signifier, such as the phallus as a fundamental signifier of the castration complex, from a person's symbolic universe. It may be a defence mechanism specific to psychosis (1), and it differs from repression inasmuch as the foreclosed signifier is not integrated into the person's unconscious and does not re-emerge from within as a neurotic (1) symptom but may return in the form of a psychotic (1) hallucination. The idea is traceable to an article in 1894 by Sigmund Freud (1856–1939) on ‘The Neuro-Psychoses of Defence’ (Standard Edition, III, pp. 45–61): ‘There is, however, a much more energetic and successful kind of defence. Here, the ego rejects the incompatible idea together with its affect and behaves as if the idea had never occurred to the ego at all’ (p. 58).