Wittgenstein finished part 1 of the in the spring of 1945. From 1946 to 1949 he worked on the philosophy of psychology almost without interruption. The present two-volume work comprises many of his writings over this period. Some of the remarks contained here were culled for part 2 of the ; others were set aside and appear in the collection known as Zettel. The great majority, however, although of excellent quality, have hitherto remained unpublished. This bilingual edition of the presents the first English translation of an essential body of Wittgenstein's work. It elaborates Wittgenstein's views on psychological concepts such as expectation, sensation, knowing how to follow a rule, and knowledge of the sensations of other persons. It also shows strong emphasis on the "anthropological" aspect of Wittgenstein's thought. Philosophers, as well as anthropologists, psychologists, and sociologists will welcome this important publication.