In the summer of 1940 Moore was invited to be Neilson Visiting Professor at Smith College, Northampton, Massachussetts, for the first semester of the academic year (see `Autobiography' and A. Lazerowitz, Jul 1940 8L/8/3). He lectured once a week on `sense-perception' and held discussion classes. He did the same at Princeton during the spring semester of 1941 (notice of appointment 9/2/4). In the summer of 1941 he was Howison Lecturer at the University of California at Berkeley, and spent the autumn semester at Mills College, near San Francisco. Early in 1942 he went to New York and lectured at Columbia University for four semesters (appointments 9/2/5 7) until his return to England in May 1944. He also lectured at Swarthmore College, Pennsylvania in the spring of 1943, and gave single lectures at many other Universities. It appears that the lecture courses were often more like seminars than formal lectures, with Moore making introductory remarks and raising questions for discussion. The lecture notes are in consequence rather short and scrappy, and many are in pencil. They were folded and put into envelopes, on which Moore wrote the place, dates and subject matter.