The best light for seeing the shadows of objects truly, is, that which comes in at a common sized window, where the sun doth not shine; I shall therefore speak of their order as seen by this kind of light: and shall take the liberty in the present and following chapter, to consider colours but as variegated shades, which together with common shades, will now be divided into two general parts or branches. The first we shall call PRIME TINTS, by which is meant any colour or colours on the surfaces of objects; and the use we shall make of these different hues will be to consider them as shades to one another. Thus gold is a shade to silver, &c. exclusive of those additional shades which may be made in any degree by the privation of light. The second branch may be called RETIRING SHADES, which gradate or go off by degrees, as figs. [84 and 85 T p. II]. These shades, as they vary more or less, produce beauty, whether they are occasioned by the privation of light, or made by the pencilings of art or nature. [Illustration: Figs. 84 and 85] When I come to treat of colouring, I shall particularly shew in what manner the gradating of prime tints serve to the making a beautiful complexion; in this place we shall only observe how nature hath by these gradating shades ornamented the surfaces of animals; fish generally have this kind of shade from their backs downward; birds have their feathers enriched with it; and many flowers, particularly the rose, shew it by the gradually-increasing colours of their leaves. The sky always gradates one way or other, and the rising or setting sun exhibits it in great perfection, the imitating of which was Claud. de Loraine's peculiar excellence, and is now Mr. Lambert's: there is so much of what is called harmony to the eye to be produced by this shade, that I believe we may venture to say, in art it is the painter's gamut, which nature has sweetly pointed out to us in what we call the eyes of a peacock's tail: and the nicest needle-workers are taught to weave it into every flower and leaf, right or wrong, as if it was as constantly to be observed as it is seen in flames of fire; because it is always found to entertain the eye. There is a sort of needle-work called Irish-stitch, done in these shades only; which pleases still, tho' it has long been out of fashion. There is so strict an analogy between shade and sound, that they may well serve to illustrate each other's qualities: for as sounds gradually decreasing and increasing give the idea of progression from, or to the ear, just so do retiring shades shew progression, by figuring it to the eye. Thus, as by objects growing still fainter, we judge of distances in prospects, so by the decreasing noise of thunder, we form the idea of its moving further from us. And with regard to their similitude in beauty, like as the gradating shade pleases the eye, so the increasing, or swelling note, delights the ear.