Johan Huizinga

Fighting, as a cultural function, presupposes limiting rules, and it requires, to a certain extent anyway, the recognition of its play-quality. We can only speak of war as a cultural function so long as it is waged within a sphere whose members regard each other as equals or antagonists with equal rights; in other words its cultural function depends on its play-quality. This condition changes as soon as war is waged outside the sphere of equals, against groups not recognized as human beings and thus deprived of human rights - barbarians, devils, heathens, heretics and "lesser breeds without the law". In such circumstances war loses its play-quality altogether and can only remain within the bounds of civilization in so far as the parties to it accept certain limitations for the sake of their own honour.