The spring of 1927 saw the start of this project, which was completed by September and published in November of the same year. Freud noted "a substantial change" that had occurred in his writings over the course of the previous ten years in the "Postscript" that he appended to his "Autobiographical Study" in 1935. "My curiosity," he said, "returned to the cultural concerns that had interested me long before, when I was a youth barely old enough to think, after making a long detour through the natural sciences, medicine, and psychotherapy." In the interim years, he had naturally mentioned these issues several times, most notably in "Totem and Taboo" (1912–1913), but it wasn't until "The Future of an Illusion" that he began the series of research.