"It is one of the merits of Max Black's companion to the Tractatus that he emphasizes the continuity of Wittgenstein's philosophical development by frequent quotation from his later writings."--New York Review of Books "Black's book is, in effect, two books in one, and each of them is very good. First, there is the useful companion to the Tractatus: the store of information that anyone who picked up the Tractatus would want to have. Second,...