by those who use them in a sense that is neither obscure nor false. But the philosopher puts them into his alembic, reduces them to their first principles, draws out of them a sense that was never meant, and so imagines that he has discovered an error of the vulgar.

I observe, secondly, That, when we consider the sensation of pain by itself, without any respect to its cause, we cannot say with propriety, that the toe is either the place, or the subject of it. But it ought to be remembered, that when we speak of pain in the toe, the sensation is combined in our thought with the cause of it, which really is in the toe. The cause and the effect are combined in one complex notion, and the same name serves for both. It is the business of the philosopher to analyse this complex notion, and to give different names to its different ingredients. He gives the name of pain to the sensation only, and the name of disorder to the unknown cause of it. Then it is evident that the disorder only is in the toe, and that it would be an error to think that the pain is in it. But we ought not to ascribe this error to the vulgar, who never made the distinction, and who under the name of pain comprehend both the sensation and its cause.

Cases sometimes happen, which give occasion even to the vulgar to distinguish the painful sensation from the disorder which is the cause of it. A man who has had his leg cut off, many years after, feels pain in a toe of that leg. The toe has now no existence; and he perceives easily, that the toe can neither be the place nor the subject of the pain which he feels; yet it is the same feeling he used to have from a hurt in the toe; and if he did not know that his leg was cut off, it would give him the same immediate conviction of some hurt or disorder in the toe.

The same phenomenon may lead the philosopher, in all cases, to distinguish sensation from perception. We say, that the man had a deceitful feeling, when he felt a pain in his toe after the leg was cut off; and we have a true meaning in saying so. But, if we will speak accurately, our sensations cannot be deceitful; they must be what we feel them to be, and can be nothing else. Where then lies the deceit? I answer, it lies not in the sensation, which is real, but in the seeming perception he had of a disorder in his toe. This perception, which nature had conjoined with the sensation, was in this instance fallacious.

The same reasoning may be applied to every phenomenon that can, with propriety, be called a deception of sense. As when one, who has the jaundice, sees a body yellow, which is really white; or when a man sees an object double, because his eyes are not both directed to it; in these, and other like cases, the sensations we have are real, and the deception is only in the perception which nature has annexed to them

Nature has connected our perception of external objects with certain sensations. If the sensation is produced, the corresponding perception follows even when there is no object, and in that case is apt to deceive us. In like manner, nature has connected our sensations with certain impressions that are made upon the nerves and brain: and, when the impression is made, from whatever cause, the corresponding sensation and perception immediately follow. Thus, in the man who feels pain in his toe after the leg is cut off, the nerve that went to the toe, part of which was cut off with the leg, had the same impression made upon the remaining part, which, in the natural state of his body, was caused by a hurt in the toe: and immediately this impression is followed by the sensation and perception which nature connected with it.

In like manner, if the same impressions, which are made at present

upon my optic nerves by the objects before me, could be made in the dark, I apprehend that I should have the same sensations, and see the same objects which I now see. The impressions and sensations would in such a case be real, and the perception only fallacious.

Let us next consider the notions which our senses give us of those attributes of bodies called powers. This is the more necessary, because power seems to imply some activity; yet we consider body as a dead inactive thing, which does not act, but may be acted upon.

Of the mechanical powers ascribed to bodies, that which is called their vis insita, or inertia, may first be considered. By this is meant, no more than that bodies never change their state of themselves, either from rest to motion, or from motion to rest, or from one degree of velocity, or one direction to another. In order to produce any such change, there must be some force impressed upon them; and the change produced is precisely proportioned to the force impressed, and in the direction of that force.

That all bodies have this property, is a matter of fact, which we learn from daily observation, as well as from the most accurate experiments. Now it seems plain, that this does not imply any activity in body, but rather the contrary. A power in body to change its state, would much rather imply activity than its continuing in the same state: so that, although this property of bodies is called their vis insita, or vis inertiæ, it implies no proper activity.

If we consider, next, the power of gravity, it is a fact, that all the bodies of our planetary system gravitate towards each other. This has been fully proved by the great Newton. But this gravitation is not conceived by that philosopher to be a power inherent in bodies, which they exert of themselves, but a force impressed upon them, to which they must necessarily yield. Whether this force be impressed by some subtile ether, or whether it be impressed by the power of the Supreme Being, or of some subordinate Spiritual Being, we do not know; but all sound natural philosophy, particularly that of Newton, supposes it to be an impressed force, and not inherent in bodies.

So that, when bodies gravitate, they do not properly act, but they are acted upon they only yield to an impression that is made upon them. It is common in language to express, by active verbs, many changes in things, wherein they are merely passive: and this way of speaking is used chiefly when the cause of the change is not obvious to sense. Thus we say, that a ship sails, when every man of common sense knows that she has no inherent power of motion, and is only driven by wind and tide. In like manner, when we say that the planets gravitate towards the sun, we mean no more, but that, by some unknown power, they are drawn or impelled in that direction.

What has been said of the power of gravitation may be applied to other mechanical powers, such as cohesion, magnetism, electricity; and no less to chemical and medical powers. By all these, certain effects are produced, upon the application of one body to another. Our senses discover the effect; but the power is latent. We know there must be a cause of the effect, and we form a relative notion of it from its effect: and very often the same name is used to signify the unknown cause, and the known effect.

We ascribe to vegetables the powers of drawing nourishment, growing and multiplying their kind. Here likewise the effect is manifest, but the cause is latent to sense. These powers, therefore, as well as all the other powers we ascribe to bodies, are unknown causes of certain known effects.

It is the business of philosophy to investigate the nature of those powers as far as we are able, but our senses leave us in the dark.

We may observe a great similarity in the notions which our senses give us of secondary qualities, of the disorders we feel in our own bodies, and of the various powers of bodies which we have enumerated. They are all obscure and relative notions, being a conception of some unknown cause of a known effect. Their names are, for the most part, common to the effect, and to its cause; and they are a proper subject of philosophical disquisition. They might therefore, I think, not improperly be called occult qualities.

This name, indeed, is fallen into disgrace since the time of Des Cartes. It is said to have been used by the Peripatetics to cloak their ignorance, and to stop all inquiry into the nature of those qualities called occult. Be it so. Let those answer for this abuse of the word who were guilty of it. To call a thing occult, if we attend to the meaning of the word, is rather modestly to confess ignorance than to cloak it. It is to point it out as a proper subject for the investigation of philosophers, whose proper business it is to better the condition of humanity, by discovering what was before hid from human knowledge.

Were I therefore to make a division of the qualities of bodies as they appear to our senses, I would divide them first into those that are manifest, and those that are occult. The manifest qualities are those which Mr. Locke calls primary; such an extension, figure, divisibility, motion, hardness, softness, fluidity. The nature of these is manifest even to sense; and the business of the philosopher with regard to them, is not to find out their nature, which is well known, but to discover the effects produced by their various combinations; and with regard to those of them which are not essential to matter, to discover their causes as far as he is able.

The second class consists of occult qualities, which may be subdivided into various kinds; as first, the secondary qualities; secondly, the disorders we feel in our own bodies; and, thirdly, all the qualities which we call powers of bodies, whether mechanical, chemical, medical, animal, or vegetable; or if there be any other powers not comprehended under these heads. Of all these the existence is manifest to sense, but the nature is occult; and here the philosopher has an ample field.

What is necessary for the conduct of our animal life, the bountiful Author of Nature hath made manifest to all men. But there are many other choice secrets of nature, the discovery of which enlarges the power, and exalts the state of man. These are left to be discovered by the proper use of our rational powers. They are hid, not that they may be always concealed from human knowledge, but that we may be excited to search for them. This is the proper business of a philosopher, and it is the glory of a man, and the best reward of his labour, to discover what Nature has thus concealed.

CHAPTER XIX.

OF MATTER AND OF SPACE.

THE objects of sense we have hitherto considered are qualities. But qualities must have a subject. We give the names of matter, material substance, and body, to the subject of sensible qualities; and it may be asked, what this matter is?

I perceive in a billiard ball, figure, colour, and motion; but the ball is not figure, nor is it colour, nor motion, nor all these taken together; it is something that has figure, and colour, and motion. This is a dictate of nature, and the belief of all mankind.

As to the nature of this something, I am afraid we can give little account of it, but that it has the qualities which our senses discover.

But how do we know that they are qualities, and cannot exist without a subject? I confess I cannot explain how we know that they cannot exist without a subject, any more than I can explain how we know that they exist. We have the information of nature for their existence; and I think we have the information of nature that they are qualities.

The belief that figure, motion, and colour, are qualities, and require a subject, must either be a judgment of nature, or it must be discovered by reason, or it must be a prejudice that has no just foundation. There are philosophers who maintain, that it is a mere prejudice; that a body is nothing but a collection of what we call sensible qualities; and that they neither have nor need any subject. This is the opinion of Bishop Berkeley and Mr. Hume; and they were led to it by finding, that they had not in their minds any idea of substance. It could neither be an idea of sensation nor of reflection.

But to me nothing seems more absurd, than that there should be extension without any thing extended; or motion without any thing moved: yet I cannot give reasons for my opinion, because it seems to me selfevident, and an immediate dictate of my nature.

And that it is the belief of all mankind, appears in the structure of all languages; in which we find adjective nouns used to express sensible qualities. It is well known that every adjective in language must belong to some substantive expressed or understood; that is, every quality must belong to some subject.

Sensible qualities make so great a part of the furniture of our minds, their kinds are so many, and their number so great, that if prejudice, and not nature, teach us to ascribe them all to a subject, it must have a great work to perform, which cannot be accomplished in a short time, nor carried on to the same pitch in every individual. We should find not individuals only, but nations and ages, differing from each other in the progress which this prejudice had made in their sentiments; but we find no such difference among men. What one man accounts a quality, all men do, and ever did.

It seems therefore to be a judgment of nature, that the things immediately perceived are qualities, which must belong to a subject; and all the information that our senses give us about this subject, is, that it is that to which such qualities belong. From this it is evident, that our notion of body or matter, as distinguished from its qualities, is a relative notion; and I am afraid it must always be obscure until men have other faculties.

The philosopher in this seems to have no advantage above the vulgar; for as they perceive colour, and figure, and motion by their senses as well as he does, and both are equally certain that there is a subject of those qualities, so the notions which both have of this subject are equally obscure. When the philosopher calls it a substratum, and a subject of inhesion, those learned words convey no meaning but what every man understands and expresses, by saying, in common language, that it is a thing extended, and solid, and moveable.

The relation which sensible qualities bear to their subject, that is, to

body, is not, however, so dark, but that it is easily distinguished from all other relations. Every man can distinguish it from the relation of an effect to its cause; of a mean to its end; or of a sign to the thing signified by it. I think it requires some ripeness of understanding to distinguish the qualities of a body from the body. Perhaps this distinction is not made by brutes, nor by infants; and if any one thinks that this distinction is not made by our senses, but by some other power of the mind, I will not dispute this point, provided it be granted, that men, when their faculties are ripe, have a natural conviction, that sensible qualities cannot exist by themselves, without some subject to which they belong.

I think, indeed, that some of the determinations we form concerning matter, cannot be deduced solely from the testimony of sense, but must be referred to some other source.

There seems to be nothing more evident, than that all bodies must consist of parts; and that every part of a body is a body, and a distinct being which may exist without the other parts; and yet I apprehend this conclusion is not deduced solely from the testimony of sense: for, besides that it is a necessary truth, and therefore no object of sense, there is a limit beyond which we cannot perceive any division of a body. The parts become too small to be perceived by our senses; but we cannot believe that it becomes then incapable of being further divided, or that such division would make it not to be a body.

We carry on the division and subdivision in our thought far beyond the reach of our senses, and we can find no end to it: nay, I think we. plainly discern, that there can be no limit beyond which the division cannot be carried.

For if there be any limit to this division, one of two things must necessarily happen: either we have come by division to a body which is extended, but has no parts, and is absolutely indivisible; or this body is divisible, but as soon as it is divided, it becomes no body. Both these positions seem to me absurd, and one or the other is the necessary consequence of supposing a limit to the divisibility of matter.

On the other hand, if it is admitted, that the divisibility of matter has no limit, it will follow, that no body can be called one individual substance. You may as well call it two, or twenty, or two hundred. For when it is divided into parts, every part is a being or substance distinct from all the other parts, and was so even before the division: any one part may continue to exist though all the other parts were annihilated.

There is, indeed, a principle, long received as an axiom in metaphysics, which I cannot reconcile to the divisibility of matter. It is, That every being is one, omne ens est unum. By which I suppose is meant, that every thing that exists must either be one indivisible being, or composed of a determinate number of indivisible beings. Thus an army may be divided into regiments, a regiment into companies, and a company into men. But here the division has its limit; for you cannot divide a man without destroying him, because he is an individual; and every thing, according to this axiom, must be an individual, or made up of individuals.

That this axiom will hold with regard to an army; and with regard to many other things, must be granted: but I require the evidence of its being applicable to all beings whatsoever.

Leibnitz, conceiving that all beings must have this metaphysical unity, was by this led to maintain, that matter, and indeed the whole universe, is made up of monads, that is, simple and indivisible substances.

Perhaps the same apprehension might lead Boscovick into his hypothesis;