Consider the following statement: Cats have four legs. This is an analytic statement, since its truth can be established by looking at the subject and predicate; one does not need to look further into the world to establish it. Its reverse: What has four legs is a cat. Is synthetic, since we need to look at the world to establish its truth value, which, in fact, is false. Now consider the following statement: What can be proved is true. Going by the usual understanding of proof and truth, one can say that this is an analytic proposition, and true. Its reverse: What is true can be proved. Seems more problematic; is it synthetic or analytic? And if so, Why?