Whence shall we take our beginning? From Space, _istud litigium philosophorum_, which leaves the mind equally dissatisfied, whether we deny or assert its real existence. To make it wholly ideal, would be at the same time to idealize all phenomena, and to undermine the very conception of an external world. To make it real, would be to assert the existence of something, with the properties of nothing. It would far transcend the height to which a physiologist must confine his flights, should we attempt to reconcile this apparent contradiction. It is the duty and the privilege of the theologian to demonstrate, that _space_ is the ideal organ by which the soul of man perceives the _omnipresence_ of the Supreme Reality, as distinct from the works, which in him move, and live, and have their being; while the equal mystery of _Time_ bears the same relation to his _Eternity_, or what is fully equivalent, his Unity. Physiologically contemplated, Nature begins, proceeds, and ends in a contradiction; for the moment of absolute solution would be that in which Nature would cease to be Nature, _i.e._ a scheme of ever-varying relations; and physiology, in the ambitious attempt to solve phenomena into absolute realities, would itself become a mere web of verbal abstractions. But it is in strict connexion with our subject, that we should make the universal FORMS as well as the not less universal LAW of Life, clear and intelligible in the example of _Time_ and _Space_, these being both the first specification of the principle, and ever after its indispensable symbols. First, a single act of self-inquiry will show the impossibility of distinctly conceiving the one without some involution of the other; either time expressed in space, in the form of the mathematical line, or space within time, as in the circle. But to form the first conception of a _real_ thing, we state both as one in the idea, _duration_. The formula is: (A=B+B=A)=(A=A) or the oneness of space and time, is the predicate of all _real_ being.