By attention to these relations the student may approximate to a just conception of the powers of colours, and, assisted by a good eye, and a knowledge of his materials, may attain to a perfect application of them; by a like attention to these powers of colours, the engraver too will be enabled to estimate those due additions of light or shade which may be necessary to compensate for the absence of colours in his performance; or, in other words, to represent them by their exact equivalents of light and shade.

It has been remarked as a common deficiency of young painters, that their figures, though well drawn, have wanted relief, and that the early works of Vandyke, Titian, and other great masters, have had the same deficiency; for the perfect management of light, shade, and colour, upon which relief depends, is ever of latest attainment, and some there are who never attain it. Yet others, unacquainted with the relations and powers of colours, and even wanting natural feeling therein, colour well by creating for themselves an artificial eye for colouring, and building on the taste and science of other masters by constantly having a finely-coloured picture as a model while painting.

This is nevertheless to be approved where science and nature are wanting, and has by persevering practice established both in the same person; for habit is art and second nature.

We may learn farther from these relations of colours, why dapplings of two or more colours produce effects in painting so much more clear and brilliant than uniform tints produced by compounding the same colours; and why hatchings, or a touch of their contrasts, thrown as it were by accident upon local tints, have the same effect; - why also, as justly remarked by Sir Joshua Reynolds, colours mixed deteriorate each other, which they do more by imperfectly neutralizing or subduing each other chromatically, than by any chemical action or discordance, though the latter is sometimes also to be taken into the account; they impress, too, on the good colourist, not only the necessity of using his colours pure, but that also of using pure colours: nevertheless, pure colouring and brilliancy differ as much from crudeness and harshness, as tone and harmony do from murki-ness and monotony, though both these have been confounded by the injudicious.

The powers of colours in contrasting each other agree with their correlative powers of light and shade, and are to be distinguished from their powers individually on the eye, which are those of light alone: thus, although orange and blue are equal powers as respects each other, as respects the eye they are totally different and opposed; for orange is a luminous colour, and acts powerfully in irritating, while blue is a shadowy colour, and acts much less powerfully, or contrarily, in soothing that organ- - it is the same, in various degrees, with other colours: these powers resolve, therefore, ultimately into the same principles of light and shade, in a sensible or latent state.

There are yet other modes of contrast or antagonism, in colouring, which claim the attention and engage the skill of the colourist. That of which we have spoken is the contrast of hues, upon which depend the brilliancy, force, and harmony of colouring; there is also the contrast of shades, to which belong all the powers of the chiaroscuro, by which term the painter denotes the harmonious effects of light and shade, which, though it is a part, and the simplest part of colouring only, and ought not to be separated from it, ranks as a distinct, and is an important, branch of painting; yet is the regimen of opposition in colours coincident with that of light and shade, or black and white; all that can be said of the latter may be said of the former - a fine eye is essential to both; and he who excels in the one is in a considerable degree qualified to surpass in the other: indeed, a just practice of light and shade might carry with it the reputation of good colouring, as it did in Rembrandt, while considerable knowledge of colouring, without the chiaroscuro, could not obtain the name of colourists for some eminent masters of the Italian schools. A third mode of contrast in colouring is that of warmth and coolness, upon which depend the toneing and general effect of a picture; besides which there is the contrast of colour and neutrality, the chromatic and achromatic, or of hue and shade, by the right management of which local colours acquire value, gradation, keeping, and connexion; whence come breadth, aerial perspective, and the due distribution of greys and shadows in a picture.

This principle of contrast applies even to individual colours, and conduces greatly to good colouring, when it is carried into the variety of hue and tint in the same colour, not only as respects their light and shade, but also in regard to warmth and coolness, and likewise to colour and neutrality. Hence the judicious landscape-painter knows how to avail himself of warmth and coolness in the juxtaposition of his greens, as well as of their lightness and darkness, or their brilliancy or brokenness, in producing the most beautiful and varied effects; which spring in other cases from a like management of blue, white, and other colours. These powers of a colour upon itself are highly important to the painter, and conduce to that gratification from fine colouring, by which a good eye is so mysteriously affected.

In landscape we find Nature employing broken colours in enharmonic consonance and variety, and, equally true to picturesque relations, she employs also broken forms and figures in conjoint E harmony with colours; occasionally throwing into the composition a regular form, or a primary colour, for the sake of animation and contrast. It is otherwise however, yet no less true to the wider laws of harmony, in another class of her beauties, as in flowers and animate nature, to which she deals not unsparingly the primary colours, alone, and in combination with regular and beautiful forms and figures; which in like manner she associates still more simply in crystals, gems, and conchal productions - true and unconfounded in all things to the laws of general harmony and order, in which man fails only when he neglects the imitation of nature. The smoothness and making out, the delicate finish and tracery, that are so essential in the latter objects, are totally out of place in landscape, and yield to broader, and, in a comprehensive sense, more refined practice and principles of harmony and accordance in forms and colours.