An Essay Concerning Human Understanding / Ein Versuch über den menschlichen Verstand. Auswahlausgabe. John Locke
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produce them, are barely privations in those Subjects, from whence our Senses derive those Ideas. These the Understanding, in its view of them, considers all as distinct positive Ideas, without taking notice of the Causes that produce them: which is an enquiry not belonging to the Idea, as it is in the Understanding; but to the nature of the things existing without us. These are two very different things, and carefully to be distinguished; it being one thing to perceive, and know the Idea of White or Black, and quite another to examine what kind of particles they must be, and how ranged in the Superficies, to make any Object appear White or Black. […]
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§ 4. If it were the design of my present Undertaking, to enquire into the natural Causes and manner of Perception, I should offer this as a reason why a privative cause might, in some cases at least, produce a positive Idea, viz. That all Sensation being produced in us, only by different degrees and modes of Motion in our animal Spirits, variously agitated by external Objects, the abatement of any former motion, must as necessarily produce a new sensation, as the variation or increase of it; and so introduce a new Idea, which depends only on a different motion of the animal Spirits in that Organ.
§ 5. But whether this be so, or no, I will not here determine, but appeal to every one’s own Experience, whether the shadow of a Man, though it consists of nothing but the absence of Light (and the more the absence of Light is, the more discernible is the shadow) does not, when a Man looks on it, cause [130]as clear and positive an Idea in his mind, as a Man himself, though covered over with clear Sun-shine? And the Picture of a Shadow, is a positive thing. Indeed, we have negative Names, which stand not directly for positive Ideas, but for their absence, such as Insipid, silence, Nihil, etc. which Words denote positive Ideas, v. g. Tast, Sound, Being, with a signification of their absence.
§ 6. And thus one may truly be said to see Darkness. For supposing a hole perfectly dark, from whence no light is reflected, ’tis certain one may see the Figure of it, or it may be Painted; or whether the Ink, I write with, makes any other Idea, is a Question. The privative causes I have here assigned of positive Ideas, are according to the common Opinion; but in truth it will be hard to determine, whether there be really any Ideas from a privative cause, till it be determined, Whether Rest be any more a privation than Motion.
§ 7. To discover the nature of our Ideas the better, and to discourse of them intelligibly, it will be convenient to distinguish them, as they are Ideas or Perceptions in our Minds; and as they are modifications of matter in the Bodies that cause such Perceptions in us: that so we may not think (as perhaps usually is done) that they are exactly the Images and Resemblances of something inherent in the subject; most of those of Sensation being in the Mind no more the likeness of something existing without us, than the Names, that stand for them, are the likeness of our Ideas, which yet upon hearing, they are apt to excite in us.
[132]§ 8. Whatsoever the Mind perceives in it self, or is the immediate object of Perception, Thought, or Understanding, that I call Idea; and the Power to produce any Idea in our mind, I call Quality of the Subject wherein that power is. Thus a Snow-ball having the power to produce in us the Ideas of White, Cold, and Round, the Powers to produce those Ideas in us, as they are in the Snow-ball, I call Qualities; and as they are Sensations, or Perceptions, in our Understandings, I call them Ideas; which Ideas, if I speak of sometimes, as in the things themselves, I would be understood to mean those Qualities in the Objects which produce them in us.
§ 9. Qualities thus considered in Bodies are, First such as are utterly inseparable from the Body, in what estate soever it be; such as in all the alterations and changes it suffers, all the force can be used upon it, it constantly keeps; and such as Sense constantly finds in every particle of Matter, which has bulk enough to be perceived, and the Mind finds inseparable from every particle of Matter, though less than to make it self singly be perceived by our Senses. v. g. Take a grain of Wheat, divide it into two parts, each part has still Solidity, Extension, Figure, and Mobility; divide it again, and it retains still the same qualities; and so divide it on, till the parts become insensible, they must retain still each of them all those qualities. For division (which is all that a Mill, or Pestel, or any other Body, does upon another, in reducing it to insensible parts) can never take [134]away either Solidity, Extension, Figure, or Mobility from any Body, but only makes two, or more distinct separate masses of Matter, of that which was but one before, all which distinct masses, reckon’d as so many distinct Bodies, after division make a certain Number. These I call original or primary Qualities of Body, which I think we may observe to produce simple Ideas in us, viz. Solidity, Extension, Figure, Motion, or rest, and Number.
§ 10. 2dly, such Qualities, which in truth are nothing in the Objects themselves, but Powers to produce various Sensations in us by their primary Qualities, i. e. by the Bulk, Figure, Texture, and Motion of their insensible parts, as Colours, Sounds, Tasts, etc. These I call secondary Qualities. To these might be added a third sort which are allowed to be barely Powers though they are as much real Qualities in the Subject, as those which I to comply with the common way of speaking call Qualities, but for distinction secondary Qualities. For the power in Fire to produce a new Colour, or consistency in Wax or Clay by its primary Qualities, is as much a quality in Fire, as the power it has to produce in me a new Idea or Sensation of warmth or burning, which I felt not before, by the same primary Qualities, viz. The Bulk, Texture, and Motion of its insensible parts.
§ 11. The next thing to be consider’d, is how Bodies produce Ideas in us, and that is manifestly by Impulse, the only way which we can conceive Bodies operate in.
[136]§ 12. If then external Objects be not united to our Minds, when they produce Ideas in it; and yet we perceive these original Qualities in such of them as singly fall under our Senses, ’tis evident, that some motion must be thence continued by our Nerves, or animal Spirits, by some parts of our Bodies, to the Brains or the seat of Sensation, there to produce in our Minds the particular Ideas we have of them. And since the Extension, Figure, Number, and Motion of Bodies of an observable bigness, may be perceived at a distance by the sight, ’tis evident some singly imperceptible Bodies must come from them to the Eyes, and thereby convey to the Brain some Motion, which produces these Ideas, which we have of them in us.
§ 13. After the same manner, that the Ideas of these original Qualities are produced in us, we may conceive, that the Ideas of secondary Qualities are also produced, viz. by the operation of insensible particles on our Senses. For it being manifest, that there are Bodies, and good store of Bodies, each whereof is so small, that we cannot, by any of our Senses, discover either their bulk, figure, or motion, as is evident in the Particles of the Air and Water, and other extremely smaller than those, perhaps, as much smaller than the Particles of Air, or Water, as the Particles of Air or Water, are smaller than Pease or Hail-stones. Let us suppose at present, that the different Motions and Figures, Bulk and Number of such Particles, affecting the several Organs of our Senses, produce in us those different Sensations, which we have from the Colours and Smells of Bodies, v. g. that a Violet, by the impulse of such insensible particles of [138]matter of peculiar figures, and bulks, and in different degrees and modifications of their Motions, causes the Ideas of the blue Colour, and sweet Scent of that Flower to be produced in our Minds. It being no more impossible, to conceive, that God should annex such Ideas to such Motions, with which they have no similitude; than that he should annex the Idea of Pain to the motion of a piece of Steel dividing our Flesh, with which that Idea hath no resemblance.
§ 14. What I have said concerning Colours and Smells, may be understood also of Tastes and Sounds, and other the like sensible Qualities; which, whatever reality we, by mistake, attribute to them, are in truth nothing in the Objects themselves, but Powers to produce various Sensations in us, and depend on those primary Qualities, viz. Bulk, Figure, Texture, and Motion of parts; as I have said.
§ 15. From whence I think