The Freudian discovery of the unconscious marks the political and theoretical development of Trotsky, who became acquainted with Freud’s theories during the period of his stay in Vienna in 1907. Trotsky was convinced that psychoanalysis could provide a decisive contribution to socialist society. In the early years of the Revolution, he proposed supplementing Freud’s theories with materialism, thereby establishing a convergence between Freudian theory of the unconscious and Pavlov’s theses of conditioned reflexes. While he believed that the construction of socialism required alliances with the most innovative sectors of science and art, he also held that one cannot proceed by forcing the scientific and cultural sphere. Although the USSR showed initial interest in psychoanalysis, the consolidation of Stalinism in the 1930s marked the repression of the Freudian movement. Trotsky in exile returned to the themes of psychoanalysis and met André Breton at Coyoacán. In their discussions, it emerged that the Freudian discovery of the unconscious allows us to understand the artistic phenomenon, although it cannot be reduced to a plan for social change and human emancipation.