Born the son of a pastor in Kesswil, Switzerland, Jung (yuung) studied medicine at the universities of Basel (1895–1900) and Zurich, where he obtained his MD in 1902. From 1902 until 1909 he worked under the direction of Eugen Bleuler at the Burghölzi Psychiatric Clinic, Zurich, while at the same time lecturing in psychiatry at the University of Zurich (1905–13). In 1907 Jung met Sigmund Freud, whose chief collaborator he became. Following the formation of the International Psycho-Analytical Association (1910) he served as its first president from 1911 until his break with Freud in 1912.

Jung continued to practice in Zurich and to develop his own system of analytical psychology. He became professor of psychology at the Federal Institute of Technology in Zurich (1933–41) and was appointed professor of medical psychology at the University of Basel in 1943 but was forced to resign almost immediately for health reasons. He continued however to write, hold regular seminars, and treat patients until he was well over 80.

Like Alfred Adler, who had broken away from Freudian orthodoxy earlier, Jung minimized the sexual cause of neuroses but, unlike Adler, he continued to emphasize the role of the unconscious. His final break with Freud followed publication of his Wandlungen und Symbole de Libido (1912) translated into English in 1916 as Psychology of the Unconscious. To the ‘personal’ unconscious of the Freudian he added the ‘collective unconscious’ stocked with a number of ‘congenital conditions of intuition’ or archetypes. In search of such archetypes Jung spent long periods with the Pueblo of Arizona, and visited Kenya, North Africa, and India, and also sought for them in dreams, folklore, and the literature of alchemy.

Jung also emphasized the importance of personality and in his Psychologische Typen (1921; Psychological Types) introduced the distinction he made between introverts and extroverts.