If you mean to represent great darkness, it must be done by contrasting it with great light; on the contrary, if you want to produce great brightness, you must oppose to it a very dark shade: so a pale yellow will cause red to appear more beautiful than if opposed to a purple colour.
There is another rule, by observing which, though you do not increase the natural beauty of the colours, yet by bringing them together they may give additional grace to each other, as green placed near red, while the effect would be quite the reverse, if placed near blue.
Harmony and grace are also produced by a judicious arrangement of colours, such as blue with pale yellow or white, and the like; as will be noticed in its place.
Chap. CCLXXII.—Of detaching the Figures.
Let the colours of which the draperies of your figures are composed, be such as to form a pleasing variety, to distinguish one from the other; and although, for the sake of harmony, they should be of the same nature[66], they must not stick together, but vary in point of light, according to the distance and interposition of the air between them. By the same rule, the outlines are to be more precise, or lost, in proportion to their distance or proximity.
Chap. CCLXXIII.—Of the Colour of Reflexes.
All reflected colours are less brilliant and strong, than those which receive a direct light, in the same proportion as there is between the light of a body and the cause of that light.
Chap. CCLXXIV.—What Body will be the most strongly tinged with the Colour of any other Object.
An opake surface will partake most of the genuine colour of the body nearest to it, because a great quantity of the species of colour will be conveyed to it; whereas such colour would be broken and disturbed if coming from a more distant object.