In psychoanalysis, the process by which ideas that have undergone repression and are constantly striving to break through into consciousness are prevented from doing so by an equal force operating in the opposite direction. It was first postulated in 1900 by Sigmund Freud (1856–1939) in his book The Interpretation of Dreams (Standard Edition, IV-V, at pp. 604–5), and it was subsequently used to explain the operation of defence mechanisms. Also called anticathexis. See also reaction formation. Compare cathexis.