This essay is adapted from Traversal.
We look at a thing — a bird, a ball, a planet — and perceive it to be a certain color. But what we are really seeing is the color that does not inhere in it—the portion of the spectrum it shirks, the wavelength of light it reflects back unabsorbed. Our world appears a swirling miracle of blue, but its blueness is only a perceptual phenomenon arising from how our particular atmosphere, with its particular chemistry and its insentient stubbornness toward a particular portion of the spectrum, absorbs and reflects light.
In the living world beneath this atmosphere that scatters the shorter wavelengths as they pass, blue is the rarest color: There is no naturally occurring true blue pigment among living creatures. In consequence, only a slender portion of plants bloom in blue, and an even more negligible number of animals are bedecked with it, all having to perform various tricks with chemistry and the physics of light, some having evolved astonishing triumphs of structural geometry and optics to render themselves blue. Each feather of the blue jay is tessellated with tiny light-reflecting beads arranged to cancel out every wavelength of light except the blue.
