After the publication of the Tractatus Logico-Philosophicus in 1921, Wittgenstein abandoned philosophy because he thought that the Tractatus gave a definitive solution to all the problems of philosophy. During the following years, however, owing to various influences, including conversations with other philosophers, he came to think that the Tractatus was seriously flawed. This led not merely to an attempt to rectify the faults in the position expounded in the Tractatus in a piecemeal fashion, but eventually to the development of a new philosophical outlook. Wittgenstein returned in 1929 to Cambridge where he taught and wrote copiously; but no work other than the Tractatus was published in his lifetime apart from a short article which he almost immediately repudiated. However, soon after Wittgenstein’s death in 1951, a work appeared that he had been preparing for publication, the Philosophical Investigations; and it is this that contains the most considered and polished statement of his later thought.