Landscape Painting/Chapter 4
IV
REFRACTION
What is refraction—refraction as applied to art? When I first had to speak to my own students of this most elusive but most important quality, I found myself curiously handicapped by the fact that there was no word in the English language to describe it. A careful search of the dictionaries revealed nothing that met the need. The French word envelope and our own "lost-edge" were descriptive of the result only and not of the cause. Neither radiation, nor reaction, nor reflection, nor ambience fully defined the thing which it was desired to describe.
Piracy seemed the only way out of the dilemma; so I boldly seized upon the word refraction and forced it willy-nilly to assume the new rôle. And while it was necessary to twist it far from its original meaning I have faith that with growing years it will come to carry gracefully the full burden of definition.
For the purposes of this paper therefore the reader will kindly assume refraction to stand for that intimate effect of one mass of color or value upon its adjoining mass which results in the "lost-edge," and a general diffusion of tone, thus giving to pictures their atmospheric quality.
Now refraction is only in a very limited sense an objective fact. It is mainly a visual fact whose operation is due to the imperfect construction of the lens of the human eye. The scientific fact is that the edges of things are sharp and hard as a rule. This is amply proved by the photographic lens, which gives us a clear-cut definition all over the plate which the human eye could never hope to compass in looking at nature through its own imperfect instrument. And if the camera were still more perfect, if there were no question of focus, it would probably give us an edge everywhere as sharp as the traditional Toledo blade.
But this scientific fact would still remain an artistic lie. Fortunately, we painters have to do only with impressions and not with realities. For these impressions we must rely solely upon the lenses which God has given us; and as a painter I congratulate myself daily that the lens of the human eye was designed not at all after the pattern of the lenses adapted to the camera, the microscope, and the various other scientific instruments. As we are now provided, nature is infinitely beautiful to us; while it might have been a hideous nightmare of sharp and cutting angles or edges, without rest or relief anywhere.
It is not necessary for our purposes to enter here into the physiological structure of the human eye. It will be enough to state that its radius of exact vision is extremely limited; so limited in fact that at a distance of six feet from the eye it would hardly be possible for any human being to enumerate accurately the spots on a target four feet in diameter, while holding the gaze rigidly fixed on the bull's-eye. Beyond the radius of twelve inches from the centre the image begins to blur, and this blur increases rapidly, until out of the tail of the eye on either side we get only an indefinite consciousness of things rather than any genuine vision of things themselves.
It is curious when you come to think of it, how many untold centuries it has taken mankind to recognize this simple visual phenomenon, which every one of the race must have been experiencing ten thousand times a day for ten million years; and how few there are even to-day who are fully cognizant of it.
A gentleman of marked intelligence and culture once berated me for what he termed the artist's impudence in giving to the public a smudge of greenish brown or of gray up against the sky and asking them to accept it as a tree. "Why," he said, "I can see every leaf on that oak tree in the meadow yonder. And so can any one whose eyesight is normal."
My reply to this was to pin a card to one of the oak's lower branches and ask my friend, standing at ten paces, to tell me how many of the leaves he could count without shifting his gaze from the white card.
"Well, by Jove!" he presently exclaimed, "I can't count up to fifty."
"What do the rest of the leaves look like," I asked, "a more or less indefinite blur?"
"Yes! Just a blur."
"Well," I said, "now you understand just a little of the meaning of the word refraction."
But the new knowledge did not seem to console him. He continued to regret the loss of all those leaves. I could not convince him that it would have been a disaster had he been obliged to see each individual leaf of all the millions which the tree doubtless carried, and in addition to this, to be conscious of all the twigs and blades of grass and other infinite details around about.
Now any interesting picture motive generally has a focus, or centre of interest on which the artist's eye rests with especial pleasure; and in view of the visual limitation just described it is evident that this portion will appear much more definite in outline than the outlying regions of the composition; which will become more and more blurred, as they recede, with the softened or lost edge everywhere. This is refraction; and as the eye sees it, so, without question, the hand should paint it.
But there are other motives—certain of Whistler's nocturnes, for instance—wherein the eye broods dreamily over the whole scene, not resting fixed upon any one given point of interest; and these should be painted precisely as Whistler painted them, the refraction distributed evenly all over the canvas. Whistler, in fact, was past master of the art of refraction, its one great and supreme prophet; and it is to the consummate and most artistic use which he made of this one quality that his work owes all of that emotional, appealing, and poetic charm which is its distinguishing trait.
Of course every artist of any training at the present day is more or less aware of this phenomenon, otherwise his pictures would not find acceptance at the hands of the juries, for they would be hopelessly hard and edgy and unatmospheric. No one, for instance, would to-day think of painting the spots of sky showing through the interstices of a large tree with the tint he had mixed for the sky out in the open on the other side of the picture. If he did so paint these spots, they would shine out like electric lights and he would instinctively lower their value at once. Here the law of refraction has come into force again, and the visual no longer accords with the actual. The sky behind the tree of course is in reality just as light as the rest of the sky, but the refraction from the surrounding dark mass of foliage has robbed the spots of much of their power of light and has softened them in every way.
But while all good painters to-day are aware of refraction, and (whether consciously or unconsciously) use it in their work, very few, I think, have any conception of the far-reaching effect and control of the law. I am myself absolutely convinced that the refraction emanating, we will say, from a large dark tree standing up against a sunset sky will affect the sky and gradually lower its value out to its very centre; and that, per contra, the darkest spot in the tree itself will be found to be near its focal point, owing to the inward refraction from the sky—for naturally refraction acts both ways, from light to dark as well as from dark to light. Whether it is necessary or advisable in practical painting to utilize the law up to the extreme limit, is of course a point that is open to discussion. As painters our business is to transmit to picture-lovers through the medium of our pictures the emotions, and the impressions of strength and power, or of poetic beauty which have come to us direct from nature; but in doing this we are not called upon to saddle ourselves with more difficulties than are absolutely necessary. Indeed it is by means of the wise selection and synthesis of the elements which are essential to his work and the ruthless elimination of all such as are unessential that the consummate artist shows his calibre. Nevertheless I can recall certain canvases by Corot, poetic masterpieces of the first order, in which the very fullest use of this law was made. It can do no harm at least for any painter to keep the law always in mind, to be used whenever its use will add an element of beauty or of distinction to his work.
In addition to the above defined theory, a long and close study of the law of refraction has left on my mind the strong conviction that the out-worn and rather cheap practice of vignetting was not without a certain sound basis of justification in the underlying laws of nature. If you will bear in mind the fact that the colors and values that are seen out of the corners of the eyes, are, on account of their very situation, able to affect only a very limited number of the sensitive nerves of the retina, you will understand that the force of their impact must be proportionately less than those which come to the eye from the full centre of vision; and if you are willing to try the experiment of looking for five minutes at a given scene in nature, keeping the gaze fixed during all that time on some focal point—a church steeple, for instance—but throwing the mind's eye constantly back and forth from outside margin to centre and from centre to outside margin again, it will gradually dawn upon you that there is an actual and very marked visual difference in the color and value intensity of the two radii. I am sure, therefore, that the eighteenth-century artists who made use of this law in their work were fundamentally correct in their intuitions; but the excess to which they carried it landed them in the quagmire of the commonplace and vulgar. Nevertheless, I am certain that no picture in its extreme corners should be painted with quite the same vigor of technique or strength of color or of value as in its natural focal centre. Indeed, a careful study of certain masterpieces shows that wonderful results have occasionally been obtained by the reserved and masterly use of this principle. In the "Shepherdess," by Millet, for instance, the sense of immensity and of limitless space which marks and distinguishes that great canvas is derived largely from the extremely subtle use to which he put his knowledge of this obscure phenomenon.
So far I have spoken of refraction only in its relation to values. But there is also color refraction; and here its action is much more in harmony with the scientific laws of color, for its first and immediate effect is to call up the complementary. I sat one day out in the blazing sunlight on the white painted deck of a river steamer holding in my hand a crimson ticket, in the centre of which a square hole had been perforated. After glancing through this hole for an instant I handed the ticket to my companion and asked her to say what color the deck appeared to be as seen through the square opening. "Why! it is brilliant green," she replied, at the same time putting the ticket aside to see if in reality the deck had been painted green in that particular spot.
This, of course, was an extreme case; the very powerful scarlet, under the compelling stress of the intense sunlight, had simply conjured up its complementary in an exceptionally 
From a photograph, copyright 1906, by N. E. Montross
D. W. Tryon—"Twilight, Autumn"
brilliant and dramatic demonstration. But in greater or less degree, the law is always at work. Any painter who has posed his sitter against a red background, for instance, must have noted how the red ground brought out the green tones in the flesh. And has it ever occurred to you why never a portrait was painted against a bright blue background. Simply because there has never been found a human being modest enough to stand for the jaundiced presentment of himself that would be the natural result—yellow being the complementary of blue.
It results from this that no color has any definite and fixed existence of its own—once it is out of the tube. It is changed and varied infinitely as its surroundings change and vary. Even when it is fixed definitely under the varnish of some masterpiece, it remains subject to the same old law, and, to a certain extent, can be made attractive and lovely, or forbidding and ugly according to the background against which the picture is hung.
Of course in the scale of subdued colors color-refraction works feebly, and it is therefore of minor importance to the landscape painter, though, as I have already noted, Corot knew how to make good use of the little crimson cap on his peasant women; for the tiny spot of red doubled the beauty of his delicate greens. But the figure painter occasionally finds a knowledge of this law of great value; as, for instance, when he wishes to play upon the emotions by the simple use of pure color. Splendid effects have been produced in this way by Monticelli, by Frank Brangwyn, and more recently by the Spaniard Sorolla. It is fortunate, perhaps, that the limits of space here draw a line, for the things that might be said about refraction are endless. I will, however, add one parting word in regard to its technical side. How may we best secure the lost-edge and the other qualities deriving from refraction while maintaining crisp drawing and a free and agreeable brushwork. In this we can hardly do better than study and follow the two great masters of the art, Corot and Whistler. Prepare for the refraction, as they did, by lowering values as you approach the edge, so that the final stroke which draws your limb or your tree may be as fresh and as crisp as possible without being hard; and if you are painting in broken color—that is, using prismatic vibration to secure luminosity—then do all this preparatory work fully and carefully in the undertone, so that the final painting may be accomplished with that dash and freedom which, say what you may, will always remain an admirable quality in a picture.