Psychology of the Unconscious is an important early work of C. G. Jung, published as Wandlungen und Symbole der Libido 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).
Jung published a revised version of the work, in German in 1952, and translated into English in 1956 as Symbols of Transformation (Collected Works Vol.5 ISBN 0-691-01815-4).
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.
According to Jung, his work is an "extended commentary on a practical analysis of the prodromal stages of schizophrenia" (Jung, [1956] 1967: xxv). The analysis is of the Miller Fantasies. These are fantasies of a woman Jung did not know, and who was only identified by the pseudonym Frank Miller. She recorded her fantasies, with her own comments and impressions, before she succumbed to an outbreak of schizophrenia. Jung explains their crucially significant mythological content and portending influence. The Miller Fantasies are included as an appendix in Symbols of Transformation.