We cannot too persistently bear in mind that there is, corresponding to the logical distinction between the analytic and the synthetic proposition, a deep and broad general difference between the wants of our nature ministered to by the formal and the applied sciences respectively. The formal sciences, incapable of adding anything to our detailed knowledge of the course of events, as we have seen, enlighten us solely as to the general laws of interconnection by which all conceivable systems of true assertions are permeated and bound together. In a different connection it would be interesting to develop further the reflection that the necessity of appealing to such formal principles in all reasoning about empirical matters of fact contains the explanation of the famous Platonic assertion that the "Idea of Good" or supreme principle of organization and order in the universe, is itself not an existent, but something ἔτι ἐπέκεινα τῆς οὐσίας (eti epekeina tês ousias), "transcending even existence," and the very similar declaration of Hegel that the question whether "God"--in the sense of such a supreme principle--exists is frivolous, inasmuch as existence (_Dasein_) is a category entirely inadequate to express the Divine nature. For my present purpose it is enough to remark that the need to which the formal sciences minister is the demand for that purely speculative satisfaction which arises from insight into the order of interconnection between the various truths which compose the totality of true knowledge. Hence it seems a mistake to say, as some theorists have done, that were we born with a complete knowledge of the course of temporal sequences throughout the universe, and a faultless memory, we should have no need of logic or metaphysics, or in fact of inference. For even a mind already in possession of all true propositions concerning the course of events, would still lack one of the requisites for complete intellectual satisfaction unless it were also aware, not only of the individual truths, but of the order of their interdependence. What Aristotle said long ago with reference to a particular instance may be equally said universally of all our empirical knowledge; "even if we stood on the moon and saw the earth intercepting the light of the sun, we should still have to ask for the reason _why_." The purposes ministered to by the empirical sciences, on the other hand, always include some reference to the actual manipulation in advance by human agency of the stream of events. We study mechanics, for instance, not merely that we may perceive the interdependence of truths, but that we may learn how to maintain a system of bodies in equilibrium, or how to move masses in a given direction with a given momentum. Hence it is true of applied science, though untrue of science as a whole, that it would become useless if the whole past and future course of events were from the first familiar to us. And, incidentally it may be observed, it is for