cause necessity obliges them to use it. And, for the same reason, savages have much more of it than civilized nations.

370. It is by natural signs chiefly, that we give force and energy to language; and the less language has of them, it is the less expressive and persuasive.

Illus. Thus, writing is less expressive than reading, and reading less expressive than speaking without book. Speaking without the proper and natural modulations, force, and variations of the voice, is a frigid and dead language, compared with that which is attended with them: it is still more expressive, when we add the language of the eyes and features; and is then only in its perfect and natural state, and attended with its proper energy, when to all these we superadd the force of action.

371. Where speech is natural, it will be an exercise, not of the voice and lungs only, but of all the muscles of the body; like that of dumb people and savages, whose language, as it has more of nature, is more expressive, and is more easily learned.

372. Artificial signs signify, they do not express; they speak to the understanding, as algebraical characters may do, but the passions, the affections, and the will, hear them not; these continue dormant and inactive, till we speak to them in the language of nature, to which they are all attention and obedience.

Corol. As men, therefore, are led by nature and necessity to converse together, they will use every means in their power to make themselves understood; and where they cannot do this by artificial signs, they will do it, as far as possible, by natural ones; and he that understands perfectly the use of natural signs, must be the best judge in all the expressive arts, such as music, painting, acting, and public speaking.

373. As in artificial signs there is often neither similitude between the sign and thing signified, nor any connexion that arises necessarily from the nature of the things; so it is also in the natural signs.

Illus. 1. The word gold has no similitude to the substance signified by it; nor is it in its own nature more fit to signify this, than any other substance: yet, by habit and custom, it suggests this,

and no other.

2. In like manner, a sensation of touch suggests hardness, although it hath neither similitude to hardness, nor, as far as we can perceive, any necessary connexion with it. (Art. 361.) The difference between these two signs, lies only in this; that, in the first, the suggestion is the effect of habit and custom; in the second, it is not the effect of habit, but of the original constitution of our minds. (Art. 365.)

374. There are different orders of natural signs, and dif

ferent classes into which they may be distinguished, whence we may more distinctly conceive the relation between our sensations and the things they suggest, and what we mean by calling sensations signs of external things. (Art. 366. Corol.)

Illus. 1. The first class of natural signs comprehends those whose connexion with the thing signified, is established by nature, but discovered only by experience. The use of genuine philosophy consists in discovering such connexions, and reducing them to general rules. What we commonly call natural causes, might, with more propriety, be called natural signs; and what we call effects, the things signified. According to this illustration, we should no longer use the popular definitions of causes, which are of two kinds; 1st, The efficient cause, which is the energy or power producing an effect. 2dly. The final cause, which is the end or purpose for which an effect is produced.

2. A second class of natural signs, is that wherein the connexion between the sign and the thing signified, is not only established by nature, but discovered to us by a natural principle, without reasoning or experience. Of this kind are the natural signs of human thoughts, purposes, and desires, which have been already mentioned as the natural language of mankind. Thus, an infant may be put into a fright by an angry countenance, and soothed again by smiles and blandishments. And a child that has a good musical ear, may be put to sleep or to dance, and may be made merry or sorrowful by the modulation of musical sounds. The principles of all the fine arts, and of what we call a fine taste, may be resolved into connexions of this kind.

3. A third class of natural signs, comprehends those which, though we never before had any notion or conception of the thing signified, do suggest it, or conjure it up, as it were, by a natural kind of magic, and at once give us a conception and create a belief of it. Thus, our sensations suggest to us a sentient being or mind to which they belong; but the conception of mind is neither an idea of sensation nor of reflection; for it is neither like any of our sensations, nor like any thing of which we are conscious. The first conception of it, as well as the belief of it, and the common relation which it bears to all that we are conscious of, or remember, is suggested to every thinking being, we do not know how. The notion of hardness in bodies, as well as the belief of it, are got in a similar manner; being, by an original principle of our nature, annexed to that sensation which we have when we feel a hard body. (Art. 373. Illus. 2.)

Corol. 1. As the first class of natural signs is the foundation of true philosophy, and the second, the foundation of the fine arts, or of taste; so the last is the foundation of common sense.

2. And by all rules of just reasoning, we must conclude, that since sensations are invariably connected with the conception and belief of external existences, this connexion is the effect of our constitution, and ought to be considered as an original principle of human nature, till we find some more general principle into which it may be resolved.

CHAPTER III.

OF MATTER AND SPACE.

375. OF MATTER. We give the names of matter, material, substance, body, to the subject of sensible qualities or properties.

Illus. 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. (Illus. Art. 182.) This is a dictate of nature, and the belief of all mankind. The essence of body is unknown to us: but we have the information of nature for the existence of those properties in matter which our senses discover.

376. 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.

Corol. 1. But extension must be in something extended, motion in something moved, colour in something coloured; and in the structure of all languages, we find adjective nouns used to express sensible qualities; but 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: therefore, our opinion, or belief, that the things immediately perceived by our senses, are qualities which must belong to a subject, is an immediate judgment of nature, not discoverable by reason, nor instilled as a prejudice that has no just foundation; and all the information our senses give us about this subject, is, that it is that to which such qualities belong.

2. From this it is evident, that our notion of body or matter, as distinguished from its qualities, is a relative notion. (Art. 365. Obs.)

Obs. The relation which sensible qualities bear to their subject, that is, to body, may be distinguished from all other relations. Thus, you can distinguish it from the relation of an effect to its cause, (Art. 14.); of a means to its end, (Art. 337. Corol.); or of a sign to the thing signified, (Art. 374.)

377. Some of the determinations, however, which we form concerning matter, cannot be deduced solely from the testimony of sense, but must be referred to some other source.

Illus. There seems to be nothing more evident, than that bodies must consist of parts, and that every part of a body is a body, and a distinct something which may exist without the other parts; and yet I apprehend this conclusion is not deducible 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.

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

Illus. For, if there be any limit to this division, one of two things must necessarily happen; either we shall 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 of these positions seem to me absurd, and one or the other is the necessary consequence of supposing a limit to the divisibility of matter.

379. 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 an individual substance; you may as well call it two, or twenty, or two hundred.

Corol. For where it is divided into parts, every part is a body or substance, distinct from all the other parts, and was so even before the division. Any one part, therefore, may continue to exist, though all the other parts were annihilated.

380. There are other determinations concerning matter, which, we apprehend, are not solely founded upon the testimony of sense.

Illus. These determinations are, that it is impossible that two bodies should occupy the same place at the same time; that the same body should be in different places at the same time; that a body can be moved from one place to another, without passing though the intermediate places either in a straight course, or by some circuit.

Corol. These appear to be necessary truths, and therefore cannot be conclusions of our senses; for our senses testify only what is, not what must necessarily be.

381. OF SPACE. Though space be not perceived by any of our senses, when all matter is removed; yet, when we perceive any of the primary qualities, space presents itself as a necessary concomitant; for there can neither be extension, nor motion, nor figure, nor divisibility, nor cohesion of parts, without space.

382. There are only two of our senses, touch and sight, by which the notion of space enters into the mind.

Illus. A man without either of these senses can have no concẹption of space. And supposing him to have both, until he sees or feels other objects, he can have no notion of space; for it has nei

ther colour nor figure to make it an object of sight; and it is no tangible quality, to make it an object of touch. But other objects of sight and touch carry the notion of space along with them, and not the notion only, but the belief of it; for a body could not exist, if there was no space to contain it; nor could it move, if there was no space; and its situation, its distance, and every relation which it has to other bodies, supposes space.

383. But though the notion of space seems not to enter at first into the mind, until it is introduced by the proper objects of sense; yet being once introduced, it remains in our conception and belief, though the objects which introdu

Iced it be removed.

Illus. We see no absurdity in supposing a body to be annihilated, but the space that contained it remains; and to suppose that annihilated, seems to be absurd. It is so much allied to nothing, or emptiness, that it seems incapable of annihilation or of creation.

384. Space not only retains a firm hold of our belief, even when we suppose all the objects that introduced it to be annihilated, but it swells to immensity. We can set no limits, either of extent or duration, to its profundity and immutability.

Corol. Hence we call it immense, eternal, immoveable, and indestructible. But it is only an immense, eternal, immoveable, and indestructible void or emptiness.

Obs. The student will here observe, that this language, though popular, is sufficiently definite, as is also our reference to the aeriform elastic fluid, that fills all space.

385. When we consider parts of space that have measure and figure, there is nothing we understand better, nothing about which we can reason so clearly and to so great an

extent.

Illus. Extension and figure are circumscribed parts of space, and are the objects of Geometry, a science in which human reason has the most ample field, and can go deeper, and with more certainty, than in any other. But when we attempt to comprehend the whole of space, and to trace it to its origin, we lose ourselves in the search. 386. The philosophers tell us, that our sight, unaided by touch, gives a very partial notion of space, but yet a distinct This partial notion they call visible space. The sense of touch, say they too, gives a much more complete notion of space; and when it is considered according to this notion, they call it tangible space.

one.

Obs. Visible figure, extension, and space, may be made the subjects of mathematical speculation, as well as the tangible. In the visible, we find two dimensions only; in the tangible, three; in the one, magnitude is measured by angles; in the other, by lines,