Page:Landscape Painting by Birge Harrison.djvu/272

LANDSCAPE PAINTING blue arch of heaven. Each rock, each tree, each waving field of grain has, of course, its fixed and definite local color, but the appearance of each of these objects changes a thousand times a day. And it is with this equation—this fleeting, intangible, ever-shifting, ever-varying appearance, that artists have to do. The facts of nature are to him nothing, the mood everything. By an ironical chance he has it in his power to convince the most uncompromising and unimaginative scientific purist of the truth of his statement that the most unquestionable facts of science are often the most shameless of visual lies—and this by the simplest sort of a scientific demonstration. In the diagram on page 213, two upright lines of equal length are traced side by side, and near enough together to allow of easy visual comparison. To No. 1 have [212]