332. In order to make the best use of colours without being under the necessity of multiplying them, as, for example, in draperies of a single colour, recourse may be had to the coloured rays emanating from neighbouring bodies, whether visible to the spectator or out of sight. For example, a green or yellow light falling upon part of a blue drapery renders it green, and by contrast heightens the blue-violet tone of the rest; a golden yellow light falling on part of a purple drapery imparts to it a golden tint, which makes the purple of the rest come out, &c. 333. The principle of harmony of contrast then procures for the painter in chiaro-’scuro the means of realising, with respect to brilliancy of colours and distinction of parts, such effects as are produced in paintings of flat tints. 334. Having treated of the utility of the law of simultaneous contrast in the intelligent use of pure opposite colours, and of colours broken by grey similarly opposed when it is required to multiply pure and varied colours, it now remains for me to treat of those cases in which the painter, desiring less diversity in the object, less variety in the colours, employs sparingly the _harmony of contrast_, preferring the _harmony of scale_ and the _harmony of hues_. 335. The greater the variety of colours and accessories in a composition, the more the eyes of the spectator are distracted, and the more difficulty is experienced in fixing attention. If then, this condition of diversity of colours and accessories is obligatory on the artist, the more obstacles there are to surmount in drawing and fixing the attention of the spectator upon the physiognomy of the figures, whether they represent the actors in a single scene, or whether they are simply portraits. In the latter case, if the model has such an ordinary physiognomy, as recommends itself neither by its expression nor its beauty, and still more, if he must conceal or dissemble a natural defect, all that is accessory to this physiognomy, all the resources of contrasted colours, well assorted, should come to his aid. 336. But if, fervently inspired, he appreciates the purity of expression, the nobility and loftiness of character pertaining to his model; or even if a physiognomy, to most eyes commonplace, strikes him by such an expression as he judges to belong only to men animated by noble ideas, it is to such a model that he will address himself and fix his chief attention; so that in giving it life upon his canvas, no one can mistake either the resemblance, or the sentiment which directed his pencil. Everything being accessory to the physiognomy, the draperies will be of black or of sombre colours; and if ornaments relieve them, they will be simple, and always in keeping with the subject.