ESSAY XII. Remarks on some Chapters of 111r. Locke's Essay on the Human Understanding. SECT. I. Of Sensible Qualities, and particularly of Colour. IT is now universally agreed among all men of reasoning and philosophy, that the sensible qualities, such as colours, sounds, smells, &c. are not really inherent in thebodies themselves, such as we perceive them, but are mere ideas arising in the mind from the different impressions made on the senses. This is excellently explained and proved beyond contradiction byMr. Locke, in his . Second Book, eighth chap. But have found one argument more for the same truth, which I th nk is equally strong, and yet different from all his. One considerable reason that will prove colour, as well as sensible qualities, not to be really inherent in the bodies them- selves, is this: that in order to the perception of different objects, or their different sensible qualities, the external organs of sense must be struck or moved in a different manner by those objects. The way whereby we perceive variety of distinct colours, is by the variety of impressions that are made upon our optic nerves by the rays of light reflected from coloured bodies ; these rays of light being reflected in various and different manners, require that the surfaces of these bodies which reflect them should be really different from each other, and be composed of particles of divers figures or sizes, situations or motions, for otherwise they could not reflect the rays of light in different manners ; nor can any distinction be made in the several impressions of red and green objects on the eye, through the common medium of air, but what arises from the various shapes and sizes, and disposi- tions of the particles that compose the surface of a red or green body ; because these little particles must variously reflect the various and different rays of light to our eyes. If therefore bo- dies of divers colours be distinguished by our sight, it must be by the distinct impressions their-surfaces makeby the rays of light on the eye ; for a mere inherent quality, br a supposed teint or dye in the bodies themselves would not diversify the reflections of light, nor do any thing towards it, if the surface of those bo- dies were of the same configuration of particles. It is plain that we might have the saine impressions made on our optic nerves, by various coloured bodies, if these colours were only inherent teints, and had no other difference in their surfaces. 'rite like
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