As our senses are carried through the varieties of a tale, so the eye must be diverted from any particular object in a picture, by judiciously absorbing or bringing into notice the accessories necessary to complete the composition, without disturbing it, or prejudicing the principal. An harmonious intimacy with all the parts, and the means of that intimacy rendered as imperceptible as possible, will absorb hardness in the masses, and give distinctness and articulation to that which should predominate in acute solidity, all disjointed and unconnected appearances being carefully guarded against. Different arrangements of the same subject will be found the best means of exemplifying this.
The shadow of a cloud may accidentally be thrown over the greatest distance, while a sunbeam may suddenly illumine the middle space or foreground: the distance then would be the darkest part of the picture. Or a gleam of light may rest upon the distant mountains, while the middle space and foreground may be in shadow; then the case would be reversed, the greatest spread of light occupying the farthest distance. Even this arrangement has succeeded with some.
The highest defined light will be that which comes boldest off the darkest part of the ground. All others will decrease in proportion, as they mingle with the ground. And, as the aforesaid light is pure, so the darks will appear darker than they are. ([Plates 5], [6].)
That part of a body in light will be the brightest that is nearest to the luminary. In the theory of light, it often happens there are double and treble reflexes, which must be stronger than single ones, and the shadows of course proportionally faint. ([Plate 4.])
In proportion as reflected lights are thrown upon a darker or lighter ground, will their appearance be more or less brilliant. We deduce from this, that all those reflexes, that brighten up and play so harmoniously among the obscurity of shadows, must be in proportion to the strength of the light that occasions them. ([Plate 4.])
The light made to graduate too softly, by means of the half-tint, into the shadow, unless some part be boldly and cuttingly opposed to the other, will have a tame and insipid appearance, however sharp and forcible other portions of the work may be. ([Plates 3], [4].)
'Fulness of effect is produced by melting and losing the shadows in a ground still darker than those shadows: whereas relief is produced by opposing and separating the ground from the figure; either by light, or shadow, or colour.' ([Plate 3, fig. 2.])
Any thing intercepting the line of light upon an object, will render its shadows soft, and its lights beautifully blended.
Accidental shadows are those occasioned by objects interposed between the light and the surface reflected on. Natural shadows, those which the light connects with every opaque body. ([Plate 4], consists of natural and accidental shadows.)
The outline of the shadow should partake of the forms, at its edges, of the character of the surface receiving, as well as the one giving it.