Civilization has little to fear from educated people and brain-workers. In them the replacement of religious motives for civilized behaviors by other, secular motives, would proceed unobtrusively. . . .
Sigmund FreudIn almost every place where we find totems we also find a law against persons of the same totem having sexual relations with one another and consequently against their marrying. This, then, is 'exogamy', an institution related to totemism.
Sigmund Freud