CHAPTER VII
TECHNICAL PRECEPTS
I
If thou wishest to model well in painting, so as to deceive the eyesight, thou must be right cunning in thy colours, and must know how to keep them distinct, in painting, one from another. For example, thou paintest two coats of mantles, one white the other red; thou must deal differently with them in shading. There is light and shadow on all things, wherever the surface foldeth or bendeth away from the eye. If this were not so, everything would look flat, and then one could distinguish nothing save only a chequerwork of colours.
If then thou art shading the white mantle, it must not be shaded with so dark a colour as the red, for it would be impossible for a white thing to yield so dark a shadow as a red. Neither could they be compared one with another, save that in total absence of daylight everything is black, seeing that colour cannot be recognised in darkness. Though, therefore, in such a case, the theory allows one, without blame, to use pure black for the shadows of a white object, yet this can seldom come to pass.
Moreover, when thou paintest anything in one colour--be it red, blue, brown, or any mixed colour--beware lest thou make it so bright in the lights that it departs from its own kind. For example, an uneducated man regardeth thy picture wherein is a red coat. "Look, good friend," saith he, "in one part the coat is of a fair red and in another it is white or pale in colour." That same is to be blamed, neither hast thou done it aright. In such a case a red object must be painted red all over and yet preserve the appearance of solidity; and so with all colours. The same must be done with the shadows, lest it be said that a fair red is soiled with black Wherefore be careful that thou shade each colour with a similar colour. Thus I hold that a yellow, to retain its kind, must be shaded with a yellow, darker toned than the principal colour. If thou shade it with green or blue, it remaineth no longer in keeping, and is no longer yellow, but becometh thereby a shot colour, like the colour of silk stuffs woven of threads of two colours, as brown and blue, brown and green, dark yellow and green, chestnut-brown and dark yellow, blue and seal red, seal red and brown, and the many other colours one sees. If a man hath such as these to paint, where the surface breaketh and bendeth away the colours divide themselves so that they can be distinguished one from another, and thus must thou paint them. But where the surface lieth flat one colour alone appeareth. Howbeit, if thou art painting such a silk and shadest it with one colour (as a brown with a blue) thou must none the less shade the blue with a deeper blue where it is needful. If often cometh to pass that such silks appear brown in the shadows, as if one colour stood before the other. If thy model beareth such a garment, thou must shade the brown with a deeper brown and not with blue. Howbeit, happen what may, every colour must in shading keep to its own class.
II
The great genius Hokusai, who has obtained for popular art in Japan a success comparable to that of the best classic masterpieces of that country and to the drawings and etchings of Rembrandt, a master of an altogether kindred nature, wrote a little treatise on the difference of aim noticeable in European and Japanese art. From the few Dutch pictures which he had been able to examine, he concluded that European art attempted to deceive the eye, whereas Japanese art laboured to express life, to suggest movement, and to harmonise colour. What is meant is easily grasped when we set before the mind's eye a picture, by Teniers and a page of Hokusai's "Mangwa." On the other hand, if one chose a sketch by Rembrandt to represent Dutch art, the difference could no longer be apparent. If the aim of European art had ever in serious examples been to deceive the eye, our painting would rank with legerdemain and Maskelyne's famous box trick; for it is to be doubted if it could ever so well have attained its end as even a second-rate conjurer can. I have cited a passage in which Reynolds confronts the work of great artists with the illusions of the camera obscura (see p. 237). The adept musical performer who reproduces the noises of a farmyard is the true parallel to the lesser Dutch artists; he deceives the ear far better than they deceive the eye. For every picture has a surface which, unless very carefully lighted, must immediately destroy the illusion, even if it were otherwise perfect. Nevertheless, Dürer in the foregoing passage seems to accept Hokusai's verdict that the aim of his painting is to deceive the eye; forgetful of all that he has elsewhere written about the necessity of beauty, the necessity of composition, the superiority of rough sketches over finished works.