Jungs hard-hitting criticism of Freud in this letter, including an accusation that he mistreated both his patients and his pupils, indicates that the relationship between the two men had soured to a point that a split between them was imminent. They had a fundamental disagreement about the role of sexuality in creating neuroses as well as other theoretical differences. Thought to have been lost when Freud left Vienna to escape the Nazis in 1938, Jungs letters were discovered in London in 1954. Freuds daughter, Anna, donated photostatic copies to the Library of Congress in 1958. The originals eventually went to the Eidgenssische Technische Hochschule (ETH, the Swiss Federal Institute of Technology) in Zurich.