What is termed the ultimate incompressibility of Matter, is an admitted law of thought. Though it is possible to imagine a piece of matter to be compressed without limit, yet however small the bulk to which we conceive it reduced, it is impossible to conceive it reduced into nothing. While we can represent to ourselves the parts of the matter as indefinitely approximated, and the space occupied as indefinitely decreased, we cannot represent to ourselves the quantity of matter as made less. To do this would imply an imagined disappearance of some of the constituent parts—would imply that some of the constituent parts were in thought compressed into nothing; which is no more possible than the compression of the whole into nothing. Whence it is an obvious corollary, that the total quantity of matter in the Universe, cannot really be conceived as diminished, any more than it can be conceived as increased. Our inability to conceive Matter becoming non-existent, is immediately consequent on the very nature of thought. Thought consists in the establishment of relations. There can be no relation established, and therefore no thought framed, when one of the related terms is absent from consciousness. Hence it is impossible to think of something becoming nothing, for the same reason that it is impossible to think of nothing becoming something—the reason, namely, that nothing cannot become an object of consciousness. The annihilation of Matter is unthinkable for the same reason that the creation of Matter is unthinkable; and its indestructibility thus becomes an _à priori_ cognition of the highest order—not one that results from a long continued registry of experiences gradually organized into an irreversible mode of thought; but one that is given in the form of all experiences whatever.