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The same water, at the same time, may produce the idea of cold by one hand and of heat by the other, but the same water cannot be both hot and cold at the same time. 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 the same water may at the same time produce the sensation of heat in one hand and cold in the other; but figure never produces the idea of square by one hand and round by the other.

The qualities that are in bodies are, 1. bulk, figure, number, situation, and motion or rest of their solid parts. These are in them whether we perceive them or no; and these I call primary qualities. 2. The power that is in any body to produce in us the ideas of color, sound, smell, taste, &c. these are called sensible qualities. 3. The power that is in any body to make a sensible change in the bulk, figure, texture, and motion of another body. 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 may be properly called primary qualities, the other two are only powers which result from the different modifications of those primary qualities.

But the second sort, viz. the power to produce ideas by our senses, are looked on as real qualities, though the third sort are esteemed barely powers. Thus light and heat are thought real qualities existing in the sun, but we look on the whiteness and softness produced in wax, not as qualities in the sun, as effects produced by powers in it; whereas our perceptions of light and heat are no more in the sun than the changes made in the melted or bleached wax.

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The reason why the one are taken for qualities and the other only for powers, is that the ideas we have of colors, sounds, &c. containing nothing of bulk, figure, or motion, we do not think them the effects

of these primary qualities; hence we imagine the ideas to be resemblances of something existing in the objects. But in the operations of bodies changing the qualities one of another, we discover in the qualities produced no resemblance to the cause producing it; for when we see wax or a fair face changed by the sun, we find not these colors in the sun itself: for our senses being able to discover the likeness or unlikeness of sensible qualities in two different external objects, we never fancy any sensible quality produced in a subject to be a quality communicated, but only an effect of bare power, unless we find such a sensible quality in the subject producing it. But our senses not discovering any unlikeness between our ideas and the qualities of objects producing them, we are apt to imagine that our ideas are resemblances of something in the objects, and not the effects of certain powers in their primary qualities.

To conclude; besides the before-mentioned primary qualities, all the rest are but powers, whereby, by immediately operating on our bodies, they produce different ideas in us; or by changing the primary qualities of other bodies, they render them capable of producing ideas in us different from what they before did. The former may be called secondary qualities, immediately perceivable; the latter, secondary qualities, mediately perceivable.

CHAPTER IX.

Of Perception.

Perception is the first faculty exercised about ideas, and is the first idea we have from reflection. It is by some called thinking, though thinking is, in strict propriety, an active operation of the mind; while, in perception, the mind is for the most part passive.

Whatever impressions are made on the body, if they are not taken notice of within, there is no perception. Fire may burn our bodies, but unless the sense of

heat, or idea of pain, be produced in the mind, there is no actual perception. How often may a man observe, that whilst the mind is intently employed, it takes no notice of the impressions of sounding bodies! An impulse is made on the organ, but not reaching the observation of the mind, no perception follows. So that wherever there is sense or perception, there some idea is actually produced, and present to the understanding.

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Children before they are born may receive some few ideas from the bodies that environ them, or from the wants and diseases they may suffer. Hunger and warmth are probably the first ideas they have. these are very far from those innate principles which some contend for; they are the effects of sensation, and differ from other ideas derived from sense only in precedence of time. As some ideas may be introduced into the minds of children previous to their birth, 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. The ideas that are most familiar at first being various according to circumstances, the order in which they come into the mind is uncertain, nor is it material to know it.

We are farther to consider concerning perception, that the ideas received by sensation are insensibly altered by the judgment. When we see a round globe, the idea imprinted on our mind is of a flat circle variously shadowed; but having been accustomed to the appearance made by convex bodies, the judgment by habitual custom alters the appearances into their causes: so that from variety of shadow it frames to itself the perception of a convex figure and uniform color; when the idea we receive thence, is only a plane variously colored; as is evident in painting. To which purpose I shall here insert a problem of the learned and worthy Mr. Molineux :- Suppose a man born blind, and now adult, and taught by his

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touch to distinguish between a cube and a sphere of the same metal, and of the same size, so as to tell, when he felt the one and the other, which is the cube and which the sphere. Suppose then the cube and sphere placed on a table, and the blind man to be made to see: Quare, whether by his sight, before he touched them, he could now distinguish, and tell, which is the globe, which the cube? To which the proposer answers, Not:' for though he has obtained the experience of how a globe, how a cube affects his touch; yet he has not yet attained the experience, that what affects his touch so or so, must affect his sight so or so; or that a protuberant angle in the cube, that pressed his hand unequally, shall appear to his eye, as it does in the cube. I agree with this gentleman, and set this down, leaving with my reader to consider how much he may be beholden to experience and acquired notions, when he thinks he has least help from them; and the rather, as this gentleman adds, that having, on the occasion of my book, proposed this to divers very ingenious men, he hardly ever met with one, that at first gave the answer to it, which he thinks true, till, by hearing his reasons, they were convinced.

But this is not usual in any of our ideas but those of sight, which is the most comprehensive of our senses, conveying to the mind the ideas of light and color, which are peculiar to that sense; and also those of space, figure, and motion, the varieties of which so change the appearance of light and color, that we bring ourselves by use to judge of the one by the other. This is done so quickly, that we take that for the perception of our sensation, which is an idea formed by our judgment. Nor need we wonder at this, when we consider how very quick are the actions of the mind; for as thought takes up no space, so its actions seem to require no time. Habits, also, produce actions in us which often escape our observation. How frequently do we cover our eyes with our eyelids

without perceiving that we are in the dark! and therefore it is not strange that our mind should often change the idea of its sensation into that of its judgment, without taking notice of it.

Perception puts the distinction betwixt the animal kingdom and the inferior parts of nature: for however vegetables may have degrees of motion, and so some have obtained the name of sensitive plants, I suppose it is all bare mechanism, and no otherwise produced than the shortening of a rope by the affusion of water, which is done without sensation. Perception is in all sorts of animals, though the sensations of some are obscure and dull compared with the quickness of others. We may conclude that an oyster has not such quick senses as a man or several other animals but there is some dull perception whereby they are distinguished from perfect insensibility.

Perception then being the first step and degree towards knowlege, and the inlet of all the materials of it, the fewer senses a man has, and the duller the impressions are that are made by them, and the duller the faculties are that are employed about them, the more remote is he from that knowlege that is to be found in some men.

CHAPTER X.

Of Retention.

The next faculty of the mind in its progress towards knowlege is retention, or the keeping the simple ideas which it receives from sensation or reflection. This is done, 1. by keeping the idea actually in view, which is called contemplation; 2. by reviving in our minds those ideas which have disappeared; this is memory, which is as it were the storehouse of our ideas for the mind not being capable of having many ideas in view at once, it was necessary to lay up those which at another time it might have use of. But this laying up of ideas signifies merely a power which the mind has of reviving perceptions, with the

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