ATUM was the creator god of Heliopolis, the sole progenitor and head of the ancient Egyptian pantheon according to one of the earliest Egyptian cosmogonies. Atum, "the all" or "the complete one," by spitting, vomiting, or masturbating produced Shu and Tefnut, "air" and "moisture," who in turn generated Geb and Nut, "earth" and "sky." This last chthonic pair produced Osiris and Seth, rivals for the rulership of the land, together with their consorts, Isis and Nephthys. Together these nine deities comprised the great Heliopolitan ennead, but probably the greatest function of this pantheon was to provide a genealogy for the Egyptian king, who was equated with Horus, the son of Isis. Horus had to avenge the slaying of his father, Osiris, by his uncle, Seth.

As early as the Old Kingdom (2686–2181 BCE) the sky god, Atum, had been assimilated to the sun god, Re. This new solar deity...