Page:Landscape Painting by Birge Harrison.djvu/85

REFRACTION 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 [55]