Opponents of same-sex marriage argue that the concept is oxymoronic. Marriage, they say, must involve a man and a woman because (1) that is the definitional essence of marriage, (2) the Judeo- Christian tradition requires it, and/or (3) the modem Western nation-state has structured society around the assumption that only different-sex marital unions are allowed. Proponents of same-sex marriage dispute and often ridicule these assertions. Thus far, neither side has analyzed these arguments in the context of the history of marriage itself. That is the project of this Article. Part II, the heart of this Article, recounts the history of same-sex marriage, synthesizing scholarship in the fields of social anthropology, ethnography, mythology, com...