Jung first met Freud in 1907, in Vienna. From the beginning of his career Jung had found the writings of Freud, Buerer, and Janet an important stimulus for his own thinking. Jung's experiments in word associations corroborated Freud's concept of repression when Freudian ideas were still unwelcome in psychiatric and academic circles. Jung championed Freud's cause at the risk of his own career and finally became a member of Freud's inner circle. They began an eight year association with considerable correspondence (Freud-Jung letters) and in 1909 they were invited by Stanley Hall to come to lecture in America at Clark University.
In spite of Jung's admiration of Freud he felt a growing frustration over the differences between their attitudes. Freud's dogmatic and positivist attitude, especially in regard to the theory of sexuality, became increasingly disturbing to Jung. That is, whenever confronted by an expression of the higher reaches of the human spirit, Freud seemed to immediately suspect underlying repressed sexuality. To Jung, Freud had substituted God with a dogmatic creed of sexuality.
The turning point in their relationship appeared during their trip to America in 1909. The two were analyzing each other's dreams. Jung at one point, as he himself reports in Memories, Dreams, Relfections, suggested to Freud that he could do a better job interpretating the dreams, if Freud would provide some additional details of his private life. Freud is said to have given him a look of suspicion and said that he could not so risk his authority. To Jung this meant that Freud had place personal locality above truth and a year later he discontinued their association. (Freud's version is that Jung had a death wish focused on his mentor). In 1914 Jung resigned as the president of the International Psychoanalytic Society and shortly thereafter withdrew as a member.
The period between 1912 and 1917 was a particularly disturbing time for Jung. It has been called his creative illness. He was overwhelmed by fantasies and dreams and found it difficult to go on with the aspects of his daily life. He determined to confront these intrusions from his unconscious and thus gave up his public appearances and his academic career. During this period he, like Freud, had a confidant with whom he was able to keep a thread to the external world. This person was Toni Wolf, a long time associate and lover.