§ 21. Ideas being thus distinguished and understood, we may be able to give an account, how the same water, at the same time, may produce the idea of cold by one hand, and of heat by the other; whereas it is impossible, that the same water, if those ideas were really in it, should, at the same time, be both hot and cold. For if we imagine warmth, as it is in our hands, to be nothing but a certain sort and degree of motion in the minute particles of our nerves, or animal spirits, we may understand how it is possible that the same water may, at the same time, produce the sensations of heat in one hand, and cold in the other; which yet figure never does, that never producing the idea of a square by one hand, which has produced the idea of a globe by another. But if the sensation of beat and cold be nothing but the increase or diminution of the motion of the minute parts of our bodies, caused by the corpuscles of any other body, it is easy to be understood, that if that motion be greater in one hand than in the other; if a body be applied to the two hands, which has in its minuter particles a greater motion than in those of one of the hands, and a less than in those of the other, it will increase the motion of the one hand, and lessen it in the other, and so cause the different sensations of heat and cold that depend thereon.

§ 22. I have, in what just goes before, been engaged in physical inquiries a little farther than perhaps I intended. But it being necessary to make the nature of sensation a little understood, and to make the difference between the qualities in bodies, and the ideas produced by them in the mind, to be distinctly conceived, without which it were impossible to discourse intelligibly of them; I hope I shall be pardoned this little excursion into natural philosophy, it being necessary in our present inquiry, to distinguish the primary and real qualities of bodies, which are always in them, (viz. solidity, extension, figure, number, and motion, or rest; and are sometimes perceived by us, viz. when the bodies they are in, are big enough singly to be discerned), from those secondary and imputed qualities, which are but the powers of several combinations of those primary ones, when they operate without being distinctly discerned; whereby we may also come to know what ideas are, and what are not, resemblances of something really existing in the bodies we denominate from them.

§ 23. Three sorts of qualities in bodies. The qualities then that are in bodies, rightly considered, are of three sorts.

First, The bulk, figure, number, situation, and motion, or rest of their solid parts: those are in them, whether we perceive them or no; and when they are of that size, that we can discover them, we

have by these an idea of the thing, as it is in itself; as is plain in artificial things. These I call primary qualities.

Secondly, The power that is in any body, by reason of its insensible primary qualities, to operate after a peculiar manner on any of our senses, and thereby produce in us the different ideas of several colours, sounds, smells, tastes, &c. These are usually called sensible qualities.

Thirdly, The power that is in any body, by reason of the particular constitution of its primary qualities, to make such a change in the bulk, figure, texture, and motion of another body, as to make it operate on our senses, differently from what it did before. Thus the sun has a power to make wax white; and fire, to make lead fluid. These are usually called powers.

The first of these, as has been said, I think, may be properly called real, original, or primary qualities, because they are in the things themselves, whether they are perceived or no; and upon their different modifications it is, that the secondary qualities depend.

The other two are only powers to act differently upon other things, which powers result from the different modifications of those primary qualities.

§ 24. The first are resemblances. The second thought resemblances, but are not. The third neither are, nor are thought so.

But though the two latter sorts of qualities are powers barely, and nothing but powers, relating to several other bodies, and resulting from the different modifications of the original qualities; yet they are generally otherwise thought of. For the second sort, viz. the powers to produce several ideas in us by our senses, are looked upon as real qualities in the things thus affecting us: but the third sort are called and esteemed barely powers, v. g. the idea of heat or light, which we receive by our eyes, or touch, from the sun, are commonly thought real qualities, existing in the sun, and something more than mere powers in it. But when we consider the sun, in reference to wax, which it melts or blanches, we look upon the whiteness and softness produced in the wax, not as qualities in the sun, but effects produced by powers in it: whereas, if rightly considered, these qualities of light and warmth, which are perceptions in me when I am warmed or enlightened by the sun, are no otherwise in the sun, than the changes made in the wax, when it is blanched or melted, are in the sun: they are all of them equally powers in the sun, depending on its primary qualities; whereby it is able, in the one case, so to alter the bulk, figure, texture, or motion of some of the insensible parts of my eyes or hands, as thereby 10 produce in me the idea of light or heat; and in the other, it is

able so to alter the bulk, figure, texture, or motion of the insensible parts of the wax, as to make them fit to produce in me the distinct ideas of white and fluid.

§ 25. The reason why the one are ordinarily taken for real qualities, and the other only for bare powers, seems to be, because the ideas we have of distinct colours, sounds, &c. containing nothing at all in them of bulk, figure, or motion, we are not apt to think them the effects of these primary qualities, which appear not, to our senses, to operate in their production; and with which they have not any apparent congruity, or conceivable connection. Hence it is, that we are so forward to imagine, that those ideas are the resemblances of something really existing in the objects themselves: since sensation discovers nothing ofbulk, figure, or motion of parts in their production; nor can reason show how bodies, by their bulk, figure, and motion should produce in the mind the ideas of blue or yellow, &c. But in the other case, in the operations of bodies changing the qualities one of another, we plainly discover that the quality produced bath commonly no resemblance with any thing in the thing producing it; wherefore we look on it as a bare effect of power. For though receiving the idea of heat or light from the sun, we are apt to think it is a perception and resemblance of such a quality in the sun; yet when we see wax, or a fair face, receive change of colour from the sun, we cannot imagine that to be the reception or resemblance of any thing in the sun, because we find not those different colours in the sun itself. For our senses being able to observe a likeness or unlikeness of sensible qualities in two different external objects, we forwardly enough conclude the production of any sensible quality in any subject, to be an effect of bare power, and not the communication of any quality, which was really in the efficient, when we find no such sensible quality in the thing that produced it. our senses not being able to discover any unlikeness between the idea produced in us, and the quality of the object producing it, we are apt to imagine that our ideas are resemblances of something in the objects, and not the effects of certain powers, placed in the modification of their primary qualities, with which primary qualities the ideas produced in us have no resemblance.

But

§ 26. Secondary qualities two-fold; first, immediately perceivable; secondly, mediately perceivable. To conclude: beside those before-mentioned primary qualities in bodies, viz. bulk, figure, extension, number, and motion of their solid parts; all the rest whereby we take notice of bodies, and distinguish them one from another, are nothing else but several powers in them, depending

on those primary qualities; whereby they are fitted, either by immediately operating on our bodies, to produce several different ideas in us; or else by operating on other bodies, so to change their primary qualities, as to render them capable of producing ideas in us, different from what before they did. The former of these, I think, may be called secondary qualities, immediately perceivable: the latter, secondary qualities, mediately perceivable.

CHAPTER IX.

OF PERCEPTION.

§ 1. Perception the first simple idea of reflection. Perception, as it is the first faculty of the mind, exercised about our ideas; so it is the first and simplest idea we have from reflection, and is by some called thinking in general. Though thinking, in the propriety of the English tongue, signifies that sort of operation in the mind about its ideas, wherein the mind is active; where it, with some degree of voluntary attention, considers any thing. For in bare naked perception, the mind is, for the most part, only passive; and what it perceives, it cannot avoid perceiving.

§ 2. Is only when the mind receives the impression. What perception is, every one will know better by reflecting on what he does himself, what he sees, hears, feels, &c., or thinks, than by any discourse of mine. Whoever reflects on what passes in his own mind, cannot miss it; and if he does not reflect, all the words in the world cannot make him have any notion of it.

§ 3. This is certain, that whatever alterations are made in the body, if they reach not the mind; whatever impressions are made on the outward parts, if they are not taken notice of within, there is no perception. Fire may burn our bodies with no other effect than it does a billet, unless the motion be continued to the brain, and there the sense of heat, or idea of pain, be produced in the mind, wherein consists actual perception.

§ 4. How often may a man observe in himself, that whilst his mind is intently employed in the contemplation of some objects, and curiously surveying some ideas that are there, it takes no notice of impressions of sounding bodies, made upon the organ of hearing, with the same alteration that uses to be for the producing the idea of sound? A sufficient impulse there may be on the organ; but if not reaching the observation of the mind, there follows no perception: and though the motion that uses to produce the idea

H

of sound, be made in the ear, yet no sound is heard. Want of sensation, in this case, is not through any defect in the organ, or that the man's ears are less affected than at other times, when he does hear: but that which uses to produce the idea, though conveyed in by the usual organ, not being taken notice of in the understanding, and so imprinting no idea in the mind, there follows no sensation. So that wherever there is sense, or perception, there some idea is actually produced, and present, in the understanding.

§ 5. Children, though they have ideas in the womb, have none innate. Therefore, I doubt not but children, by the exercise of their senses about objects that affect them in the womb, receive some few ideas before they are born, as the unavoidable effects either of the bodies that environ them, or else of those wants or diseases they suffer; amongst which (if one may conjecture concerning things not very capable of examination) I think the ideas of hunger and warmth, are two; which, probably, are some of the first that children have, and which they scarce ever part with again.

§ 6. But though it be reasonable to imagine that children receive some ideas before they come into the world, yet those simple ideas are far from those innate principles which some contend for, and we, above, have rejected. These, here mentioned, being the effects of sensation, are only from some affections of the body, which happen to them there, and so depend on something exterior to the mind; no otherwise differing in their manner of production from other ideas derived from sense, but only in the precedency of time; whereas, those innate principles are supposed to be quite of another nature; not coming into the mind by any accidental alterations in, or operations on, the body; but, as it were, original characters impressed upon it in the very first moment of its being and constitution.

§ 7. Which ideas first, is not evident. As there are some ideas, which we may reasonably suppose may be introduced into the minds of children in the womb, subservient to the necessities of their life and being there; so, after they are born, those ideas are the earliest imprinted, which happen to be the sensible qualities which first occur to them: amongst which, light is not the least considerable, nor of the weakest efficacy. And how covetous the mind is, to be furnished with all such ideas as have no pain accompanying them, may be a little guessed, by what is observable in children new born, who always turn their eyes to that part from whence the light comes, lay them how you please. But the ideas that are most familiar at first, being various, according to the divers