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S. 21. Ideas being thus distinguished and understood, we may be able to give an account how the same water, at the same time, nay 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 heat and cold be nothing but the increase or dininution 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 minute 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.
§. 29. 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 inputed qualities, which are but the
powers of several combinations of those primary ones,
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 pro. duce 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 power's result from the different modifications of those primary qualities. The first are §. 2+. But though the two latter sorts resemblances. of qualities are powers barely, and nothing The second but powers, relating to several other bothought re.
dies, and resulting from the different modisemblances, but are not.
fications of the original qualities; yet they The third are generally otherwise thought of For
the second sort, viz. the powers to pro-
as thereby to produce in me the idea of light or heat; e B and in the other it is able so to alter the bulk, figure, ma texture; or motion of the insensible parts of the wax,
as to make them fit to produce in me the distinct ideas o problem of white and fluid.
V. 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 ap
pear not, to our senses, to operate in their production; pro and with which they have not any apparent congruity,
1. Of conceivable connexion. Hence it is that we are so para forward to imagine, that those ideas are the resem
blances of something really existing in the objects themselves; since sensation discovers nothing of bulk, hgure, or motion of parts in their production ; nor can reason show how bodies, by their bulk, figure, and moI 4
tion, 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 hath com. monly no resemblance with any thing in the thing pro. ducing 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. But 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. Secondary S. 26. To conclude, beside those before. qualities two- mentioned primary qualities in bodies, viz. fold; hrst; bulk. figure, extension, number, and moimmediately perceivable': tion of their solid parts; all the rest whereby secondly, me. we take notice of bodies, and distinguish diately per. them one from another, are nothing else ceivable. 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, dif
ferent from what before they did. The former of these, I think, may be called secondary qualities, immediately perceivable: the latter, secondary qualities, mediately perceivable.
CHA P. IX.
9, 1. DERCEPTION, as it is the first
T faculty of the mind, exercised the first sim about our ideas, so it is the first and sim- ple idea of plest ideą we have from reflection, and is reflection, by some called thinking in general. Though thinking, in the propriety of the English tongue, signifies that sąrt 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 per
passive; and on the mind
§. 2. What perception is, every one will
Is only when know better by reflecting on what he does the mind rea himself, what he sees, hcars, feels, &c. or çeives the thinks, than by any discourse of mine. impression. 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 hiin 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 perceptiou. 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