Chap. CCVI.—How to make Objects detach from their Ground, that is to say, from the Surface on which they are painted.
Objects contrasted with a light ground will appear much more detached than those which are placed against a dark one. The reason is, that if you wish to give relief to your figures, you will make those parts which are the farthest from the light, participate the least of it; therefore they will remain the darkest, and every distinction of outline would be lost in the general mass of shadows. But to give it grace, roundness, and effect, those dark shades are always attended by reflexes, or else they would either cut too hard upon the ground, or stick to it, by the similarity of shade, and relieve the less as the ground is darker; for at some distance nothing would be seen but the light parts, therefore your figures would appear mutilated of all that remains lost in the back-ground.
CONTRASTE AND EFFECT.
Chap. CCVII.—A Precept.
Figures will have more grace, placed in the open and general light, than in any particular or small one; because the powerful and extended light will surround and embrace the objects: and works done in that kind of light appear pleasant and graceful when placed at a distance[43], while those which are drawn in a narrow light, will receive great force of shadow, but will never appear at a great distance, but as painted objects.
Chap. CCVIII.—Of the Interposition of transparent Bodies between the Eye and the Object.
The greater the transparent interposition is between the eye and the object, the more the colour of that object will participate of, or be changed into that of the transparent medium [44].
When an opake body is situated between the eye and the luminary, so that the central line of the one passes also through the centre of the other, that object will be entirely deprived of light.