Grigg, Russell. Lacan, Language and Philosophy. New York: SUNY Press, 2008.
Thus “foreclosure” refers not to the fact that a speaker makes a statement that declares something impossible — a process closer to disavowal — but to the fact that the speaker lacks the very linguistic means for making the statement at all.
This is where the difference between repression and foreclosure lies. On Lacan’s analysis of Freud’s classic studies on the unconscious —The Interpretation of Dreams, The Psychopathology of Everyday Life, Jokes and Their Relation to the Unconscious— The mechanisms of repression and the return of the repressed are linguistic in nature. His thesis that the unconscious is structured like a language implies the claim that for something to be repressed it has first of all to be registered in the symbolic. Thus repression implies the prior recognition of the repressed in the symbolic system or register. In psychosis, on the other hand, the necessary signifiers are lacking altogether, and so the recognition required for repression is impossible. However, what is foreclosed does not simply disappear altogether but may return albeit in a different form, from outside the subject (4).