The Voices of Wittgenstein brings for the first time in both the original German and English translation over one hundred short essays in philosophical logic and the philosophy of mind of historical importance to understanding Wittgenstein's philosophical thought and development in the 1930s. Transcribed from the papers of Friedrich Waismann and dating from 1932 to 1935, the majority are highly important dictations by Wittgenstein to Waismann, but also includes texts of redrafted material by Waismann, closely based on the dictations. Many of these texts become the ultimate sources of material on philosophy of language that constitutes the bulk of Waismann's book Logic, Sprache, Philosophy (The Principles of Linguistic Philosophy). The transcriptions throw new light on the development of Wittgenstein's thought in this period and some of the topics are not covered in any of the existing publications of his writings, in particular his detailed attention to causal theories of meaning. They also contain texts covering psychological concepts such as expecting, intending and experience; these have no counterparts in Waismann's publications. The Voices of Wittgenstein is the only substantial corpus of Wittgenstein's work that has been hitherto unknown and completely available. It will be a major primary text for all scholars of Wittgenstein and an invaluable introduction and background to Wittgenstein's philosophy.