This book includes most of the contents of a number of notebooks kept by Frederick Waismann between 1929 and 1932, in which he recorded the views communicated by Wittgenstein to Waismann himself and to Moritz Schlick. The material takes a variety of forms: some of it consists of converstaions between the three, some of questions by Waismann and Schlick with answers from Wittgenstein, some of Wittgenstein's comments on passages read to him by Waismann or on works by himself or others that had evidently been mentioned. Much of it is simply an account of Wittgenstein's views evidently taken down as he expressed them in a vivid, conversational style.