In Bruno and Campanella we find an interest in certain problems of thought, which we may call either religious or, more technically, ontological: the problems of the relations of being and knowing. In Vico, who is infinitely nearer to Croce in intellectual temper, the centre of interest is shifted. Vico is apparently satisfied with Catholicism as a religion; and he spends all his efforts in creating a philosophy out of the purely humanistic and historical side of Renaissance culture. And yet, long before Kant's _Prolegomena,_ he foresees the necessity of the new metaphysics being the metaphysics, as he says, of human ideas, and his theory of knowledge is founded on a principle which bears an external resemblance to certain aspects of pragmatism, but is in reality of a quite different, and much deeper, character: that of the interchangeability of the _factum_ with the _verum,_ of that which we make with that which we know. It was a commonplace of the schools that perfect science is to be found in God only who is the author of all things: Vico transfers this logical formula from God to man, and applies it, in the first stage of his thought, to mathematics, which appears to him as of man's own _making,_ in a narrow and abstract sense, and later to the whole world of history and human thought and action, which, in a much truer and broader sense, is _made_ by man. Vico was brought to this second and final form of his theory of knowledge by his studies on the history of law, of religion, of language and poetry: his philosophy is essentially a philosophy of the moral sciences, of philology in its widest meaning. And the whole of his speculation, in his Scienza Nuova takes the shape of an enquiry into the origins and development of human society: not essentially of a sociology, an empirical and inductive science of man (though this aspect is undoubtedly also present in his mind), but rather, through "the unity of the human spirit that informs and gives life to this world of nations," of an ideal and eternal history of mankind, a philosophy of the human mind. A contemporary and an antagonist of Descartes, Vico is one of the last among European philosophers to embrace practically the whole range of contemporary culture. But while Descartes lays the foundations of his theory of knowledge on the certainty of mathematical method, mistrusting the imperfection and vagueness of any other form of science, Vico is enabled by his intimate contact with rhetoric and history, with that _philology_ which had been the soul of the intellectual life of the Renaissance, and which through the erudition of his century was preparing the historical consciousness of the following one, to anticipate the general principles of idealistic philosophy and, on the theories of art, of language, of law, of religion, as well as on a large number of particular historical problems, the general development of subsequent European thought.