Lawren P. Harris

THE SKY IS BLUE because the many particles and gases in our atmosphere scatter sunlight, resulting in a total spectrum of visible light that appears blue to our eyes. There is no pigment in the sky, just like there is no pigment in the wings of bluebirds or buntings—the surface structure of their feathers consists of proteins and air pockets that combine to reflect the precise wavelengths of sapphire and indigo light. If you were to mash their wings, you would create a colourless paste. The blue—is only in your head.