The fundamental principle of philosophical Pantheism is either _the unity of substance_, as taught by Spinoza, or _the identity of existence and thought_, as taught, with some important variations, by Fichte, Schelling, and Hegel. The Absolute is conceived of, not as a living Being to whom a proper personality and certain intelligible attributes may be ascribed, but as a vague, indeterminate _somewhat_, which has no distinctive character, and of which, in the first instance, or prior to its development, almost nothing can be either affirmed or denied. But this absolute existence, by some unknown, inherent necessity, develops, determines, and limits itself: it becomes being, and constitutes all being: the infinite passes into the finite, the absolute into the relative, the necessary into the contingent, the one into the many; all other existences are only so many modes or forms of its manifestation. Here is a theory which, to say the very least, is neither more intelligible, nor less mysterious, than any article of the Christian faith. And what are the proofs to which it appeals, what the principles on which it rests? Its two fundamental positions are these; that finite things have no distinct existence as realities in nature, and that there exists only one Absolute Being, manifesting itself in a variety of forms. And how are they demonstrated? Simply by the affirmation of universal "Identity." But what if this affirmation be denied? What if, founding on the clearest data of consciousness, we refuse to acknowledge that _existence_ is identical with _thought_?[141] What if we continue to believe that there are objects of thought which are distinct from thought itself, and which must be _presented_ to the mind before they can be _represented_ by the mind? What if, while we recognize the idea both of the finite and the infinite, the relative and the absolute, the contingent and the necessary, we cannot, by the utmost effort of our reason, obliterate the difference between them, so as to reduce them to one absolute essence? Then the whole superstructure of Pantheism falls along with the Idealism on which it depends; and it is found to be, not a solid and enduring system of truth, but a frail edifice, ingeniously constructed out of the mere abstractions of the human mind.