Geggus asks why vodou, alone among the neo-African religions of the Americas, became the faith of a national majority, and finds the answer in an unusual combination of circumstances.

Africans made up well over half the non-white population of Saint-Domingue in the 1790s, and nothing much stood against them: after the Jesuits were expelled in the 1760s, and through the long rupture with Rome that lasted until 1860, efforts to christianise the rural population were slight. Yet baptism and priests kept their prestige, and many Central African captives arrived already carrying some Christianity from Portuguese and Italian missions, which made the fusing of Catholic ritual with African rites easier than a simple model of acculturation allows.

Turning to the colonial record, he works chiefly from Moreau de Saint-Méry's account of a snake cult in the west province, associated with Aja-Fon captives the colonists called Arada, and follows its vocabulary and its serpent deity back toward Whydah.