Colours placed in shadow will preserve more or less of their original beauty, as they are more or less immersed in the shade. But colours situated in a light space will shew their natural beauty in proportion to the brightness of that light. Some say, that there is as great variety in the colours of shadows, as in the colours of objects shaded by them. It may be answered, that colours placed in shadow will shew less variety amongst themselves as the shadows are darker. We shall soon convince ourselves of this truth, if, from a large square, we look through the open door of a church, where pictures, though enriched with a variety of colours, appear all clothed in darkness.
Chap. CCXLIII.—Whether it be possible for all Colours to appear alike by means of the same Shadow.
It is very possible that all the different colours may be changed into that of a general shadow; as is manifest in the darkness of a cloudy night, in which neither the shape nor colour of bodies is distinguished. Total darkness being nothing but a privation of the primitive and reflected lights, by which the form and colour of bodies are seen; it is evident, that the cause being removed the effect ceases, and the objects are entirely lost to the sight.
Chap. CCXLIV.—Why White is not reckoned among the Colours.
White is not a colour, but has the power of receiving all the other colours. When it is placed in a high situation in the country, all its shades are azure; according to the fourth proposition[59], which says, that the surface of any opake body participates of the colour of any other body sending the light to it. Therefore white being deprived of the light of the sun by the interposition of any other body, will remain white; if exposed to the sun on one side, and to the open air on the other, it will participate both of the colour of the sun and of the air. That side which is not opposed to the sun, will be shaded of the colour of the air. And if this white were not surrounded by green fields all the way to the horizon, nor could receive any light from that horizon, without doubt it would appear of one simple and uniform colour, viz. that of the air.
Chap. CCXLV.—Of Colours.
The light of the fire tinges every thing of a reddish yellow; but this will hardly appear evident, if we do not make the comparison with the daylight. Towards the close of the evening this is easily done; but more certainly after the morning twilight; and the difference will be clearly distinguished in a dark room, when a little glimpse of daylight strikes upon any part of the room, and there still remains a candle burning. Without such a trial the difference is hardly perceivable, particularly in those colours which have most similarity; such as white and yellow, light green and light blue; because the light which strikes the blue, being yellow, will naturally turn it green; as we have said in another place[60], that a mixture of blue and yellow produces green. And if to a green colour you add some yellow, it will make it of a more beautiful green.
Chap. CCXLVI.—Of the Colouring of remote Objects.
The painter, who is to represent objects at some distance from the eye, ought merely to convey the idea of general undetermined masses, making choice, for that purpose, of cloudy weather, or towards the evening, and avoiding, as was said before, to mark the lights and shadows too strong on the extremities; because they would in that case appear like spots of difficult execution, and without grace. He ought to remember, that the shadows are never to be of such a quality, as to obliterate the proper colour, in which they originated; if the situation of the coloured body be not in total darkness. He ought to mark no outline, not to make the hair stringy, and not to touch with pure white, any but those things which in themselves are white; in short, the lightest touch upon any particular object ought to denote the beauty of its proper and natural colour.