  Wright said that natural selection is a manifestation of the all-pervasive principle of utility, which governs adaptation. Utility he characterized in this way: “Let the questions of the uses of life, then, be put in this shape: To what ascertainable form or phase of life is this or that other form or phase of life valuable or serviceable?” (L 274–75). Features or parts of a living thing are forms or phases of life that serve the organism's more general functions and its survival. Perception of colors, for instance, serves to avoid the effects of dispersion of light in perception and to make possible definition of objects in vision through limits in sensibility (L 279). Using teleological language without teleological intent, he said, “Colors were invented by Nature to avoid the confusing effects of dispersion” (L 279). The physical laws of optics in this case lend themselves to an adaptation useful to living things.