We are to seek therefore for some absolute truth capable of communicating to other positions a certainty, which it has not itself borrowed; a truth self-grounded, unconditional and known by its own light. In short, we have to find a somewhat which is, simply because it is. In order to be such, it must be one which is its own predicate, so far at least that all other nominal predicates must be modes and repetitions of itself. Its existence too must be such, as to preclude the possibility of requiring a cause or antecedent without an absurdity. THESIS IV That there can be but one such principle, may be proved a priori; for were there two or more, each must refer to some other, by which its equality is affirmed; consequently neither would be self-established, as the hypothesis demands. And a posteriori, it will be proved by the principle itself when it is discovered, as involving universal antecedence in its very conception. SCHOLIUM. If we affirm of a board that it is blue, the predicate (blue) is accidental, and not implied in the subject, board. If we affirm of a circle that it is equi-radial, the predicate indeed is implied in the definition of the subject; but the existence of the subject itself is contingent, and supposes both a cause and a percipient. The same reasoning will apply to the indefinite number of supposed indemonstrable truths exempted from the profane approach of philosophic investigation by the amiable Beattie, and other less eloquent and not more profound inaugurators of common sense on the throne of philosophy; a fruitless attempt, were it only that it is the two-fold function of philosophy to reconcile reason with common sense, and to elevate common sense into reason. THESIS V Such a principle cannot be any THING or OBJECT. Each thing is what it is in consequence of some other thing. An infinite, independent [52] thing, is no less a contradiction, than an infinite circle or a sideless triangle. Besides a thing is that, which is capable of being an object which itself is not the sole percipient. But an object is inconceivable without a subject as its antithesis. Omne perceptum percipientem supponit. But neither can the principle be found in a subject as a subject, contra-distinguished from an object: for unicuique percipienti aliquid objicitur perceptum. It is to be found therefore neither in object nor subject taken separately, and consequently, as no other third is conceivable, it must be found in that which is neither subject nor object exclusively, but which is the identity of both. THESIS VI