In this volume, Maria Cerezo examines Wittgenstein's Tractatus Logico-Philosophicus as a response to some of Frege's and Russel's logical problems. In analyzing the tractarian conditions for the possibility of language, she explains the two main theories of the proposition in Tractatus: the truth-functions theory and the picture theory. Cerezo shows that Wittgenstein initially separates the account of the structure of a proposition from the explanation of its expression. However, contrary to his intention, the combination of these theories creates new difficulties, since the requirements of each theory cannot be fully respected by the others. Cerezo also argues that Wittgenstein's theory of language cannot be fully understood unless attention is paid to his theory of expression and his doctrine of projection by the metaphysical subject.