You may apply these same tests everywhere in nature. Even in a gray day, when the sun is not so positive a factor in distributing light, and the shadows are so subtle that it is difficult to discover them, there is always some mass of foliage, the silver sheen from an old shingled roof, the glare of a white wall, which marks for the composition its lightest light, while a corresponding dark can always be found somewhere in the tree-trunks, under the overhanging eaves, or in the broken crevices of the masonry.
So it is with every other expression of nature. Even on a Venetian lagoon, where the sky and water are apparently one (not really one to the quick eye of an expert, the water always being one tone lower than the sky—that is, more gray than the overbending sky)—even in this lagoon you will find some one portion of the surface lighter than any other portion; and in expressing it your eye first and your brush next must catch in the opalescent sweep of delicious color under your eye its exact quantity of black and white. By black and white I mean, of course, that excess or absence of pure color which when translated into pure black and white would express the meaning of the subject-matter, as one of Raphael Morghen's engravings on steel gives you the feeling and color in his masterly rendering of Da Vinci's "Last Supper."
In my judgment one of the great landscapes of modern times is the picture by the distinguished Dutch painter, Mauve, known as "Changing Pasture," which is now owned by Mr. Charles P. Taft, of Cincinnati. Here the factor of mass is carried to its utmost limit. Sky one mass; flock of sheep another mass; and the foreground, sweeping under the sheep and beyond until it is lost in the haze of the distance, another mass, or, if one chooses to put it that way, another broad gradation of a section of the picture: the highest light being some infinitesimal speck in the diaphanous silver sky, the strongest dark being found somewhere in the foreground or in the flock of sheep.
By a strict adherence to this law of one supreme light and one supreme dark does Mauve's work, as it were, get back from and out of his canvas, as from the record of a phonograph into which some soul has breathed its own precise purpose and intent.
So, too, does nature often call out to you fixing your attention, often shrouding in shadow the unimportant in the landscape, while high up above the gloom it holds up to your gaze a white candle of a minaret or the bared breast of an Alpine peak reflecting the loving look of a tired sunbeam bidding it good-night.
To accent the more strongly the value of this dominant light even though it be treated in very low gradation, I recall that a year ago the art world was startled by the sum received for a medium sized picture of some coryphées painted by Degas, now an old man over eighty years old—a subject which he always loved and, indeed, which he has painted many times. Some thirty years ago, when he was comparatively a young man, I saw, at the Bartholdi exhibition in New York, a picture by this master of these same coryphées, two figures standing together in the flies resting their weary, pink, fishworm legs as they balanced themselves with their hands against the wabbling scenery. It was a wholly gray picture, and almost in a monotone, and yet the flashes of their diamond earrings, no larger than the point of a pin, were distinctly visible, holding their place in, if not dominating, the whole color scheme.
Again, in that marvellous portrait of Wertheimer, the bric-à-brac dealer, if you remember, the eye first catches the strong vermilion touch on the lower lip, and then, knowing that a master like Sargent would not leave it isolated, one finds, to one's delight and joy, a little swipe of red on the tongue of the barely discernible black poodle squatting at his feet. Had the red of the dog's tongue predominated, we should never have been thrilled and fascinated by one of the great portraits of this or any other time.
This is also true in other great portraits—in, for instance, the pictures of Rembrandt, Vandyck, and Frans Hals, especially where a face is relieved by the addition of a hand and the white of a ruff. Somewhere in that warm expanse of the face there can be found a pinhead of color, brighter and more dominating than any other brush touch on the canvas. It may be the high egg-light in the forehead, or the click on the tip of the nose, or a fold of the white ruff; but slight as it is and unnoticeable at first, because of it not only does the head look round as the egg looks round when relieved by the same treatment, but the attention is fixed. Unless this had been preserved, the eye would have, perhaps, rested first on the hand, something foreign to the painter's intention.
Recalling again the law of the high light and strong dark, and referring again to the value of the skilful manipulation of light and shade forming the mass thereby expressing the more clearly the meaning of a picture, I repeat that, while the eye is always caught by the strongest dark against the strongest light, it is next caught by the lesser supplementary light and lesser supplementary dark; and then, if the painter is skilful enough in the management of the remaining lesser lights and darks, the eye will run through the gradations to the end, rebounding once more to the greater light and dark, exactly in the order intended by the painter; thus unfolding to the spectator little by little, quite as a plot of a novel is made clear, the story which the painter had in his own mind to tell. This is effected purely and entirely by the correct accentuations of the explanatory lights and darks. One mistake in the management—that is, the accentuating of the third light, if you please, instead of the second—will not only confuse the eye of the spectator, but may perhaps give him an entirely different impression from what was intended by the painter, just as the shifting of a chapter in a novel would confuse a reader; and this, if you please, without depending in any way upon either the drawing or the color of the accessories.