The Hegelian philosophy is an attempt to combine criticism with system, and thus realise what Kant had at least foretold. It is a system which is self-critical, and systematic only through the absoluteness of its criticism. In Hegel’s own phrase, it is an immanent and an incessant dialectic, which from first to last allows finality to no dogmatic rest, but carries out Kant’s description of an Age of Criticism, in which nothing, however majestic and sacred its authority, can plead for exception from the all-testing _Elenchus_. Then, on the other hand, Hegel refuses to restrict philosophy and its branches to anything short of the totality. He takes in its full sense that often-used phrase—the Unity of Knowledge. Logic becomes the all-embracing research of “first principles,”—the principles which regulate physics and ethics. The old divisions between logic and metaphysic, between induction and deduction, between theory of reasoning and theory of knowledge,—divisions which those who most employed them were never able to show the reason and purpose of—because indeed they had grown up at various times and by “natural selection” through a vast mass of incidents: these are superseded and merged in one continuous theory of real knowledge considered under its abstract or formal aspect,—of organised and known reality in its underlying thought-system. But these first principles were only an abstraction from complete reality—the reality which nature has when unified by mind—and they presuppose the total from which they are derived. The realm of pure thought is only the ghost of the Idea—of the unity and reality of knowledge, and it must be reindued with its flesh and blood. The logical world is (in Kantian phrase) only the _possibility_ of Nature and Mind. It comes first—because it is a system of First Principles: but these first principles could only be elicited by a philosophy which has realised the meaning of a mental experience, gathered by interpreting the facts of Nature.