_Idea of Space._--When we contemplate any material object, any existence of which the senses can take cognizance, we are cognizant of it as _extended_, _i. e._, _occupying space_, nor can we possibly conceive of it as otherwise. The idea of space, then, is involved in the very idea of extended substance, or material existence, given along with it, impossible to be separated from it. We may regard it, therefore, as _the condition or postulate of being, considered as material existence, possessing extension_, etc. The idea of it is essential to the idea of matter, the reality of it to the reality of matter; for if there were no space, there could be no extension in space, and, without extension, no matter. _Not a mere Conception._--Is space, then, a mere conception of the mind, merely subjective? Unquestionably not. It is not, indeed, a _substance_ or _entity_, it has no _being_. It is not matter, for it is, itself, the _condition_ of matter; it is not spirit, for then it were intelligent. It is not an _existence_, then, strictly speaking, not a thing created, nor is it in the power of deity either to create or to annihilate it, for creation and annihilation relate only to _existence_. And yet space is a _reality_, and not a _mere conception_ of the mind. For, if so, then were there no longer any mind to conceive it, there would be no longer any space; if no mind to think, then no thought. Were the whole race of intelligent beings, then, to be blotted out of existence, and all things else to remain as now, space would be gone, while, yet, matter would exist, extension--worlds moving on as before. Extension in what, motion in what? Not in space, for that is no longer extant; defunct, rather, with the last mind whose expiring torch went out in the gloom of night. Unless we make _matter_, then, to be also a mere conception of the mind, space is not so. If the one is real, the other is. If one is a mere conception, so is the other; and to this result the school of Kant actually come. Matter, itself, is a subjective phenomenon, a mode of mind, or, rather, if it be any thing more, we have no means of knowing it to be so. If, on the contrary, as we hold, matter _exists_, and is an object of immediate perception by the senses, then there is such a thing as space also, the _condition_ of its existence, a _reality_, though not an _entity_, the idea of it given along with that of matter, the reality of it implied in the reality of matter. Matter _presupposes_ it, depends on it as its _sine quâ non_. It depends on nothing. Were there no matter, there would be none the less space, but only space unoccupied. In that case, the idea of space might never occur to any mind, but the reality would exist just as now. Were all matter and all mind to be blotted out of being, space would still be what it is now.