The next thing to be considered is, an appropriate effect of light or shadow, to be given to the scene, or object, treated.
Calmness and serenity are the result of horizontal lights, or shadows; while the contrary is the effect of oblique, or abrupt and irregular; such as are seen in the stormy effects of Salvator Rosa, &c.
The sky and clouds are often resorted to for effect, when the landscape does not admit of sufficient. Again, less imposition thrown into the sky, will repose the landscape, when it happens to be invested with sufficient interest of itself.
Extending the repose of a work,—by throwing into the general mass of shadow a number of objects that may appear of the least consequence to the development of its story, and bringing those which should be most prominent boldly forth into the light, by projecting their forms from the hollows of the shadows, that may appear to teem with a multitude of mysterious forms, while the cutting edges and sharp lights of those projections come out in sunshine, depending solely on their vigorous division,—is one of the greatest difficulties in composition, and is principally rendered so by the necessity of adapting its sympathies to the subject we would place before the beholder—by its agreeable disposition and management; at the same time preserving the utmost singleness of intention and simplicity, by avoiding confusion, and supporting its breadth by the shapes of the masses of one and of the other. A very small portion of the light, striking some object placed in the shadow, will carry the light into it; while some point or figure, enveloped in shade or dark local colour, will be sufficient to convey the obscure parts into the luminous, and preserve the balance of the whole. ([Plate 3, fig. 2.])
The most complicated outline may by this means be reduced to the broadest effect of light and shade. And simple and palpable as this principle may seem, it may be pursued until the artist is enabled to conceal entirely the art by which it is effected; until he feels that which he could not perhaps explain, but may paint in a language that all may read.
Sir Joshua Reynolds speaks of 'That breadth of light and shadow,—that art and management of uniting light to light, and shadow to shadow, so as to make the object rise out of the ground in the plenitude of effect.'
Outline is cold and determined in its appearance, and would seem so though drawn with vermilion; and, from its being defined, carries away all idea of space and extent with it. The greater the absence of outline, the greater will be the breadth. Where there is a necessity for much outline, large masses of it must be collected into broad portions of the shadows and lights, which should be well diversified in their forms. ([Plate 5.])
Where light joins darkness, the light and dark are most intense at their junction, arising from affinity of contrast. It is not necessary to enter into the phenomena of vision to prove the existence of any thing that will be found in this work, its details being drawn from every-day observation.
Light and Shade should always, I think, partake of the character of the subject: a fête champetre should not be enveloped in the gloom of shadowy obscurity, any more than a storm piece should be clothed in the glories of sunshine.
When the composition consists of a number of objects, the best way is to single out those that should most attract, by giving them the highest quality of the light; while whole portions may be disposed of by connecting them in broad masses of the secondary light, and further uniting them with the trees, buildings, or any other objects that occur, to extend its quantity; while the masses of shadow are formed by the union of other several parts, the light mingling with and intersecting the shade, until the whole present an harmonious breadth. But to achieve this, so that the parts take agreeable forms—sustaining and supporting, and giving value to each other—is perhaps the chef-d'œuvre of the arduous arrangement of light and shade. ([Plate 2, fig. 5.])