Jung devoted the rest of his life to developing his ideas, especially those on the relation between psychology and religion. In his view, obscure and often neglected texts of writers in the past shed unexpected light not only on Jung’s own dreams and fantasies but also on those of his patients; he thought it necessary for the successful practice of their art that psychotherapists become familiar with writings of the old masters.

Besides the development of new psychotherapeutic methods that derived from his own experience and the theories developed from them, Jung gave fresh importance to the so-called Hermetic tradition. He conceived that the Christian religion was part of a historic process necessary for the development of consciousness, and he also thought that the heretical movements, starting with gnosticism and ending in alchemy, were manifestations of unconscious archetypal elements not adequately expressed in the mainstream forms of Christianity. He was particularly impressed with his finding that alchemical-like symbols could be found frequently in modern dreams and fantasies, and he thought that alchemists had constructed a kind of textbook of the collective unconscious. He expounded on this in 4 out of the 18 volumes that make up his Collected Works.

His historical studies aided him in pioneering the psychotherapy of the middle-aged and elderly, especially those who felt their lives had lost meaning. He helped them to appreciate the place of their lives in the sequence of history. Most of these patients had lost their religious belief; Jung found that if they could discover their own myth as expressed in dream and imagination they would become more complete personalities. He called this process individuation.

In later years he became professor of psychology at the Federal Polytechnical University in Zürich (1933–41) and professor of medical psychology at the University of Basel (1943). His personal experience, his continued psychotherapeutic practice, and his wide knowledge of history placed him in a unique position to comment on current events. As early as 1918 he had begun to think that Germany held a special position in Europe; the Nazi revolution was, therefore, highly significant for him, and he delivered a number of hotly contested views that led to his being wrongly branded as a Nazi sympathizer. Jung lived to the age of 85.

The authoritative English collection of all Jung’s published writings is Herbert Read, Michael Fordham, and Gerhard Adler (eds.), The Collected Works of C.G. Jung, trans. by R.F.C. Hull, 20 vol., 2nd ed. (1966–79). Jung’s The Psychology of the Unconscious appears in revised form as Symbols of Transformation in the Collected Works. His other major individual publications include Über die Psychologie der Dementia Praecox (1907; The Psychology of Dementia Praecox); Versuch einer Darstellung der psychoanalytischen Theorie (1913; The Theory of Psychoanalysis); Collected Papers on Analytical Psychology (1916); Two Essays on Analytical Psychology (1928); Das Geheimnis der goldenen Blüte (1929; The Secret of the Golden Flower); Modern Man in Search of a Soul (1933), a collection of essays covering topics from dream analysis and literature to the psychology of religion; Psychology and Religion (1938); Psychologie und Alchemie (1944; Psychology and Alchemy); and Aion: Untersuchungen zur Symbolgeschichte (1951; Aion: Researches into the Phenomenology of the Self). Jung’s Erinnerungen, Träume, Gedanken (1962; Memories, Dreams, Reflections) is fascinating semiautobiographical reading, partly written by Jung himself and partly recorded by his secretary.

In 2009 a manuscript that Jung wrote during the years 1914–30 was published in the original German with English translation as The Red Book = Liber Novus. It was, by Jung’s own description, a record of his “confrontation with the unconscious.” The work contains an account of his imaginings, fantasies, and induced hallucinations and his own colour illustrations.