The absence from matter of any such substance is evidenced by the absurdity involved in the idea of its presence. Suppose the substance to exist: the qualities inherent in it must needs be as completely distinct from itself as pins are from a pincushion; the extension and solidity of an extended, solid substance can no more be identical with the substance than the nominative is identical with the genitive case. The substance, therefore, although deprived of all its qualities will still retain its essence unimpaired, will still be equally a substance, just as a pincushion continues equally a pincushion after its last pin has been abstracted. Conceive, then, all the qualities of matter to be abstracted, and consider what remains--a substance without qualities of any sort. But a substance neither solid, nor fluid, nor yet gaseous; neither coloured nor colourless; neither singular nor plural; without form and void, without even extension--what is it? not something, but nothing; a nonentity or non-existence. The qualities of matter in being removed from the substance have therefore left nothing behind, and, consequently, although carrying with them nothing but themselves, have yet carried with them all the constituents of matter, which is thus seen to be composed exclusively of qualities without a single particle of foreign admixture. And since, moreover, the qualities of matter are clearly not themselves substances, that is to say do not themselves _stand under_ or uphold anything, it follows that their compound, matter, must likewise be purely unsubstantial. The edifice begun by Descartes has now been raised high and strong enough to have its layer of negations crowned with an affirmation of pre-eminent importance. The qualities of matter, being known only by their effects, are evidently causes: and, being causes, must necessarily be either themselves forces, or, at the least, manifestations of force; and inasmuch as force involves exertion, it cannot be inert; and inasmuch as deadness must be incapable of exertion, all force must be alive; and life without substance cannot be conceived otherwise than as some species of spirit or mind. Such therefore must be matter. Matter can be nothing else than pure spirit of some kind.