Page:Landscape Painting by Birge Harrison.djvu/36



are all born color-blind. The most perfect eyes in the world cannot see one-quarter of the colors which are known to exist in nature. Those of us who are fortunate, it is true, are able to differentiate with reasonable exactness the three primary colors which go to make up our limited human color-scale—but what about the tones which certainly exist above the ultra-violet band and below the infra-red?

For convenience, the full color-scale of nature may be divided into four octaves, of which less than one-quarter is taken up by the prismatic scale of the rainbow, which includes all the colors