Psychology of the Unconscious (German: Wandlungen und Symbole der Libido) is an early work of Carl Jung, first published in 1912. The English translation by Beatrice M. Hinkle appeared in 1916 under the full title of Psychology of the Unconscious: a study of the transformations and symbolisms of the libido, a contribution to the history of the evolution of thought (London: Kegan Paul Trench Trubner). Hinkle's translation was reissued in 1992 as supplementary volume B to The Collected Works of C. G. Jung. In 1952 Jung published a thoroughly revised version of the work, which was translated into English in 1956 as Symbols of Transformation, and reissued as volume five of the Collected Works. The book illustrates a theoretical divergence between Jung and Freud on the nature of the libido, and its publication led to a break in the friendship between the two men, both stating that the other was unable to admit he could possibly be wrong.