343. I believe that those painters who will study the mixed and simultaneous contrasts of colours, in order to employ rationally the coloured elements of their palette, will perfect themselves in _absolute colouring_ as by studying the principles of geometry they perfect themselves in linear perspective. I have no doubt but that the difficulty encountered by painters ignorant of the law of contrast, of faithfully imitating their model, has been with many the cause of a colouring dull and inferior to that of artists, who, less careful than they in the fidelity of imitation, or not so well organized for seizing all the modifications of light, have worked more by their first impressions, or, in other words, seeing the model more rapidly, their eyes have not had time to become fatigued; and thus, content with the imitation which they have made, they have not returned to their work too often to modify, to efface, and afterwards to reproduce it upon a canvas soiled by the colours first put on. There are, indeed, many painters, to whom the maxim, “Let well alone,” is peculiarly applicable. SECOND DIVISION. _Imitation of Coloured Objects by Materials of a Definite Size, as Threads, &c_. 344. The tapestries of Gobelins and of Beauvais, and also the carpets of Savonnerie, and certain very elaborate mosaics, may all be considered as works which resemble the method of painting in _chiaro-’scuro_; while the windows of Gothic churches correspond more or less exactly to painting in _flat tints_; so also with tapestries for furniture and carpets, which, instead of being fabricated with scales of at least sixteen or eighteen tones, as they are in the royal manufactories, are composed with scales consisting of three or four tones only, and, far from imitating the effects of _chiaro-’scuro_, the coloured objects produced present to the eye only small monochromous bands of a single tone. 345. There are also some works whose coloured designs are upon a kind of mixed system, being the result of the juxtaposition of monochromous single tinted parts, of a visible size, but in which the effects of _chiaro-’scuro_ are sought by using gradations of scale or a mixture of hues; such are ordinary mosaics, carpets, embroidered tapestries, &c.