Lévi-Strauss defines and distinguishes between nature and culture. Marriage rules establish culture by creating social organization based on exchanges of women. The incest prohibition affirms 'the pre-eminence of the social over the natural' (i.e., over incestuous wishes), and is the most focused part of the social systems of exchange. Marriage and initiations resolve the parent's as well as the child's incestuous problems. The child passes from the parent to the social orbit; in return, the parent is entitled to someone else's child.