Thus it is evident that the human mind is in possession of two distinct orders of primitive cognitions,--one, contingent, relative, and phenomenal; the other universal, necessary, and absolute. These two distinct orders of cognition presuppose the existence in man of two distinct faculties or organs of knowledge--_sensation_, external and internal, which perceives the contingent, relative, and phenomenal, and _reason_, which apprehends the universal, necessary, and absolute. The knowledge which is derived from sensation and experience is called _empirical_ knowledge, or knowledge _à posteriori_, because subsequent to, and consequent upon, the exercise of the faculties of observation. The knowledge derived from reason is called _transcendental_ knowledge, or knowledge _à priori_, because it furnishes laws to, and governs the exercise of the faculties of observation and thought, and is not the result of their exercise. The sensibility brings the mind into relation with the _physical_ world, the reason puts mind in communication with the _intelligible_ world--the sphere of _à priori_ principles, of necessary and absolute truths, which depend upon neither the world nor the conscious self, and which reveal to man the existence of the soul, nature, and God. Every distinct fact of consciousness is thus at once _psychological_ and _ontological_, and contains these three fundamental ideas, which we can not go beyond, or cancel by any possible analysis--the _soul_, with its faculties; _matter_, with its qualities; _God_, with his perfections. We do not profess to be able to give a clear explication and complete enumeration of all the ideas of reason, and of the necessary and universal principles or axioms which are grounded on these ideas. This is still the grand desideratum of metaphysical science. Its achievement will give us a primordial logic, which shall be as exact in its procedure and as certain in its conclusions as the mathematical sciences. Meantime, it may be affirmed that philosophic analysis, in the person of Plato, Aristotle, Kant, and Cousin, has succeeded in disengaging such _à priori_ ideas, and formulating such principles and laws of thought, as lead infallibly to the cognition of the _Absolute Being_, the _Absolute Reason_, the _Absolute Good_, that is, GOD. It would carry us too far beyond our present design were we to exhibit, in each instance, the process of _immediate abstraction_ by which the contingent and relative element of knowledge is eliminated, and the necessary and absolute principle is disengaged. We shall simply state the method, and show its application by a single illustration.