‘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.
‘10. They who assert that figure, motion, and the rest of the primary or original qualities do exist without the mind, in unthinking substances, do at the same time acknowledge that colours, sounds, heat, cold, &c. do not, which they tell us are sensations existing in the mind alone, that depend on, and are occasioned by the different size, texture, motion, &c. of the minute particles of matter. This they take for an undoubted truth, which they can demonstrate beyond all exception. Now if it be certain that those original qualities are inseparably united with the other sensible qualities, and not, even in thought, capable of being abstracted from them, it plainly follows that they exist only in the mind. But I desire any one to reflect and try whether he can, by any abstraction of thought, conceive the extension and motion of a body, without all other sensible qualities. For my own part, I see evidently that it is not in my power to form an idea of a body extended and moving, but I must withal give it some colour or other sensible quality, which is acknowledged to exist only in the mind. In short, extension, figure, and motion, abstracted from all other qualities, are inconceivable. Where, therefore, the other sensible qualities are, there must these be also, i.e. in the mind, and no where else.
‘11. Again, great and small, swift and slow, are allowed to exist nowhere without the mind, being entirely relative, and changing as the frame or position of the organs of sense varies. The extension, therefore, which exists without the mind, is neither great nor small, the motion neither swift nor slow; that is, they are nothing at all. But, say you, they are extension in general and motion in general. Thus we see how much the tenet of extended, moveable substances, existing without the mind, depends on that strange doctrine of abstract ideas. And here I cannot but remark, how nearly the vague and indeterminate description of matter, or corporeal substance, which the modern philosophers are run into by their own principles, resembles that antiquated and so much ridiculed notion of materia prima, to be met with in Aristotle and his followers. Without extension, solidity cannot be conceived; since, therefore, it has been shown that extension exists not in an unthinking substance, the same must also be true of solidity.
‘12. That number is entirely the creature of the mind, even though the other qualities be allowed to exist without it, will be evident to whoever considers that the same thing bears a different denomination of number, as the mind views it with different aspects. Thus the same extension is one, or three, or thirty-six, according as the mind considers it with reference to a yard, a foot, or an inch. Number is so visibly relative, and dependent on men’s understandings, that it is strange to think how any one should give it an absolute existence without the mind. We say one book, one page, one line, &c., all these are equally units, though some contain several of the others; and in each instance it is plain the unit relates to some particular combination of ideas arbitrarily put together by the mind.
‘13. Unity, I know, some will have to be a simple or uncompounded idea, accompanying all other ideas into the mind. That I have any such idea answering the word unity I do not find, and if I had, methinks I could not miss finding it; on the contrary, it should be the most familiar to my understanding, since it is said to accompany all other ideas, and to be perceived by all the ways of sensation and reflection.[[6]] To say no more, it is an abstract idea.
‘14. I shall farther add, that after the same manner as modern philosophers prove colours, tastes, &c., to have no existence in matter, or without the mind, the same thing may be likewise proved of all other sensible qualities whatever. Thus for instance, it is said, that heat and cold are affections only of the mind, and not at all patterns of real beings existing in the corporeal substances which excite them, for that the same body which appears cold to one hand, seems warm to another. Now, why may we not as well argue, that figure and extension are not patterns or resemblances of qualities existing in matter, because to the same eye at different stations, or eyes of a different texture at the same station, they appear various, and cannot therefore be the images of any thing settled and determinate without the mind? Again, ’tis proved that sweetness is not really in the sapid thing, because the thing remaining unaltered, the sweetness is changed into bitter, as in case of a fever, or otherwise vitiated palate. Is it not as reasonable to say, that motion is not without the mind, since if the succession of ideas in the mind become swifter, the motion, it is acknowledged, shall appear slower without any external alteration.
‘15. In short, let any one consider those arguments which are thought manifestly to prove that colours, tastes, &c. exist only in the mind, and he will find they may with equal force be brought to prove the same thing of extension, figure, and motion. Though it must be confessed this method of arguing does not so much prove that there is no extension, colour, &c. in an outward object, as that we do not know by sense which is the true extension or colour of the object. But the foregoing arguments plainly show it to be impossible that any colour or extension at all, or other sensible quality whatsoever, should exist in an unthinking subject without the mind, or in truth, that there should be any such thing as an outward object.’—Principles of Human Knowledge, pp. 54, &c.
Again, he says, page 58:—
‘But though it were possible that solid, figured movable substances may exist without the mind, corresponding to the ideas we have of bodies, yet how is it possible for us to know this? Either we must know it by sense or by reason. As for our senses, by them we have the knowledge only of our sensations, ideas, or those things that are immediately perceived by sense, call them what you will; but they do not inform us that things exist without the mind, or unperceived, like to those which are perceived. This the materialists themselves acknowledge. It remains, therefore, that if we have any knowledge at all of external things, it must be by reason, inferring their existence from what is immediately perceived by sense. But I do not see what reason can induce us to believe the existence of bodies without the mind, from what we perceive, since the very patrons of matter themselves do not pretend there is any necessary connexion betwixt them and our ideas. I say it is granted on all hands (and what happens in dreams, frenzies, and the like, puts it beyond dispute) that it is possible we might be affected with all the ideas we have now, though there were no bodies existing without resembling them. Hence it is evident the supposition of external bodies is not necessary for the producing our ideas, since it is granted they are produced sometimes, and might possibly be produced always, in the same order we see them in at present, without their concurrence. But though we might possibly have all our sensations without them, yet perhaps it may be thought easier to conceive and explain the manner of their production, by supposing external bodies in their likeness rather than otherwise, and so it might be at least probable there are such things as bodies that excite their ideas in our minds. But neither can this be said, for though we give the materialists their external bodies, they, by their own confession, are never the nearer knowing how our ideas are produced, since they own themselves unable to comprehend in what manner body can act upon spirit, or how it is possible it should imprint any idea in the mind. Hence it is evident the production of ideas or sensations in our minds, can be no reason why we should suppose matter or corporeal substances, since that is acknowledged to remain equally inexplicable with, or without this supposition. If therefore it were possible for bodies to exist without the mind, yet to hold they do so, must needs be a very precarious opinion; since it is to suppose, without any reason at all, that God has created innumerable beings that are entirely useless, and serve to no manner of purpose.