Carl Jung was born in Switzerland in 1875. He worked at a hospital in Zurich and his research resulted in the publication of Studies in Word Association (1904) and The Psychology of Dementia Pracecox (1906).

Jung read the works of Sigmund Freud who had developed the theory and practice of psychoanalysis. Freud believed that everyday actions are determined by motives which are far more numerous and complex than people realize. He claimed that the most basic and constant motives which influence our actions are unconscious and therefore are difficult to know or acknowledge. Jung met Freud and along with Alfred Adler, Erich Fromm and Karen Horney established the International Psychoanalytical Association.

Jung served as president of the International Psychoanalytical Association until the publication of his book, The Psychology of the Unconscious (1912) caused the two men to disagree about the theory of psychoanalysis.

Jung lectured at the University of Zurich (1933-41) and the University of Basle (1944-1961) and during this period developed his own school of psychology. He also introduced the idea of introvert and extrovert personalities.

Other books by Jung include Psychology and Religion (1937), Psychology and Alchemy (1944), Aion (1951), The Undiscovered Self (1957) and an autobiography, Memories, Dreams, Reflections (1962).

Carl Jung died in 1961.