held the propositions of the Tractatus to be ambiguously both true and nonsensical, at once. While the propositions could not be, by self-application of the attendant philosophy of the Tractatus, true (or even sensical), it was only the philosophy of the Tractatus itself that could render them so. This is presumably what made Wittgenstein compelled to accept the philosophy of the Tractatus as specially having solved the problems of philosophy. It is the philosophy of the Tractatus, alone, that can solve the problems. Indeed, the philosophy of the Tractatus is for Wittgenstein, on this view, problematic only when applied to itself. At the end of the text Wittgenstein uses an analogy from Arthur Schopenhauer and compares the book to a ladder that must be thrown away after it has been climbed. Proposition 7 As the last line in the book, proposition 7 has no supplementary propositions. It ends the book with the proposition "Whereof one cannot speak, thereof one must be silent" (). Picture theory A prominent view set out in the Tractatus is the picture theory, sometimes called the picture theory of language. The picture theory is a proposed explanation of the capacity of language and thought to represent the world. Although something need not be a proposition to represent something in the world, Wittgenstein was largely concerned with the way propositions function as representations. According to the theory, propositions can "picture" the world as being a certain way, and thus accurately represent it either truly or falsely. If someone thinks the proposition, "There is a tree in the yard", then that proposition accurately pictures the world if and only if there is a tree in the yard. One aspect of pictures which Wittgenstein finds particularly illuminating in comparison with language is the fact that we can directly see in the picture what situation it depicts without knowing if the situation actually obtains. This allows Wittgenstein to explain how false propositions can have meaning (a problem which Russell struggled with for many years): just as we can see directly from the picture the situation which it depicts without knowing if it in fact obtains, analogously, when we understand a proposition we grasp its truth conditions or its sense, that is, we know what the world must be like if it is true, without knowing if it is in fact true (TLP 4.024, 4.431). It is believed that Wittgenstein was