In 1921, Tractatus Logico-Philosophicus, Ludwig Wittgenstein abandoned philosophy because he thought that the Tractatus gave a definitive solution to all the problems of philosophy. The Philosophical Investigations aims to make explicit that philosophy involves using language in ways that are different from their normal employment; also that philosophy does not pick out some essential core meaning of expressions. If anything binds together the later philosophy, it is anti-essentialism. Wittgenstein also opposes the idea that philosophy is a kind of super-science in either its methods or its problems. Wittgenstein is adamant that he is not putting forward philosophical theories. Wittgenstein refers to the variety of kinds of ways that language can be used and the functions it can have as 'language-games'. Wittgenstein's position is that there is nothing that underlies the whole of language which explains its meaning. Language forms a patchwork of logically related activities which, unlike games, more than merely resemble one another: they are interrelated.