Black and white are colours found in nature in relatively pure condition; think of ebony and ivory. These two contrasted colours have been found universally to be convenient, for cave paintings first, and for identifying the two sides in games that oppose two players, such as chess, checkers or backgammon. They were therefore put to frequent use in all cultures. The sharpness of the contrast also caused the two words to become overlaid with qualitative oppositions: dirty and clean, impure and pure, bad and good. In time the adjectives were used to sharpen the contrast between the colour of people's skins. The pink-beige tone of some became labelled “white” and the darker tones of others “black.” Once used to designate what came to be called races, the originally innocent and perceptually helpful contrast between the two colours served to justify oppression and crimes, by offering an apparently natural legitimation.

The process illustrates a common bent of language: to carve out distinct realities, to spread clear ideas, to essentialize and substantialize. These processes lay the ground for sharpening of differences, and can hence-forth serve as grounds of all-out oppositions and total wars. Adjectives and nouns are particularly liable to such distortions. No such extreme contrasts are found in nature, if perceived with an innocent eye. As the folk poet in Rio put it: black hens lay white eggs.