The work of Ludwig Wittgenstein is a strange product of hard reasoning and brilliant imagination. Besides, Wittgenstein produced not one but two highly original philosophies at different times in his life. Both must be understood, and reconciled. In this book David Pears analyses Wittgenstein's two major works, the Tractatus Logico-Philisophicus and the Philosophical Investigations, and sets his conclusions against the background of the striking changes in the nature of philosophy in this century.