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

And

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. 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 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.* To say no more, it is an abstract idea.

This relates to what Mr Locke says of unity, whom all succeeding writers have made a point of bringing forward on all occasions, merely for the purpose of differing from him. They set him up as the standard, or ne plus ultra of profound wisdom, and yet they always contrive to go beyond him. I will just add, by the bye, on this argument about number, that the fair way of putting it is by asking whether one combination of ideas is not different from another, or whether one foot or one inch is the same with thirty-six feet, or thirty-six inches, not whether one foot is the same as thirty-six inches. Otherwise there will remain a real distinction of number, both in idea and in fact.

"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 argu

ments 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?

reason.

Either we must know it by sense or by

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.