This third volume of the monumental commentary on Wittgensteina s Philosophical Investigations covers sections 243--427, which constitute the heart of the book. Like the previous volumes, it consists of philosophical essays and exegesis. The thirteen essays cover all the major themes of this part of Wittgensteina s masterpiece: the private language arguments, privacy, avowals and descriptions, private ostensive definition, criteria, minds and machines, behavior and behaviorism, the self, the inner and the outer, thinking, consciounesss, and the imagination. The exegesis clarifies and evaluates Wittgensteina s arguments, drawing extensively on all the unpublished papers, examining the evolution of his ideas in manuscript sources and definitively settling many controversies about the interpretation of the published text. This commentary, like its predecessors, is indispensable for the study of Wittgenstein and is essential reading for students of the philosophy of mind. A fourth and final volume, entitled Wittgenstein: Mind and Will will complete the commentary.