‘7. From what has been said, it is evident there is not any other substance than spirit, or that which perceives. But for the fuller demonstration of this point, let it be considered, the sensible qualities are colour, figure, motion, smell, taste, &c.; _i.e._ the ideas perceived by sense. Now, for an idea to exist in an unperceiving thing is a manifest contradiction; for to have an idea is all one as to perceive; that, therefore, wherein colour, figure, &c. exist must perceive them. Hence it is clear there can be no unthinking substance or _substratum_ of those ideas. ‘8. But, say you, though the ideas themselves do not exist without the mind, yet there may be things like them whereof they are copies or resemblances, which things exist without the mind, in an unthinking substance. I answer, an idea can be like nothing but an idea, a colour or figure, can be like nothing but another colour or figure. If we look but never so little into our thoughts, we shall find it impossible for us to conceive a likeness except only between our ideas. Again, I ask whether those supposed originals, or external things, of which our ideas are the pictures or representations, be themselves perceivable or no? If they are, then they are ideas, and we have gained our point; but if you say they are not, I appeal to any one whether it be sense to assert a colour is like something which is invisible: hard or soft, like something which is intangible, and so of the rest. ‘9. Some there are who make a distinction between _primary_ and _secondary_ qualities; by the former, they mean extension, figure, motion, rest, solidity or impenetrability, and number; by the latter, they denote all other sensible qualities, as colours, sounds, tastes, &c. The ideas we have of these they acknowledge not to be the resemblances of any thing existing without the mind, or unperceived, but they will have our ideas of the primary qualities to be patterns or images of things which exist without the mind, in an unthinking substance, which they call _matter_. By matter, therefore, we are to understand an inert, useless substance, in which extension, figure, motion, &c. do actually subsist. But it is evident from what we have already shewn, that extension, figure, and motion are only ideas existing in the mind, and that consequently neither they nor their archetypes can exist in an unperceiving substance. Hence it is plain that the very notion of what is called _matter_ or _corporeal substance_ involves a contradiction in it, insomuch that I should not think it necessary to spend more time in exposing its absurdity; but because the tenet of the existence of matter seems to have taken so deep a root in the minds of philosophers, and draws after it so many ill consequences, I choose rather to be thought prolix and tedious, than omit any thing that might conduce to the full discovery and extirpation of that prejudice.