In 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 FreudJust as a satisfaction of instinct spells happiness for us, so severe suffering is caused us if the external world lets us starve, if it refuses to sate our needs. One may therefore hope to be freed from a part of one's sufferings by influencing the instinctual impulses.
Sigmund Freud