In early civilizations ideas about the structure and origin of the universe were articulated in the form of myths or sacred narratives. Such an approach was inevitable given that the universe was believed to be animated and controlled by supernatural forces. Because of this, it is impossible to divorce the investigation of ancient cosmologies from the study of religious beliefs.

John Baines (1991b) has suggested that the ancient Egyptians did not record myths systematically because myths and dogmas were not as central to Egyptian religion as cults and rituals. Inadequate recording and preservation of myths are serious problems in the study of all early civilizations. Yet myths that are reasonably well recorded also tend to be highly variable. Within early civilizations, beliefs relating to the structure and creation of the universe varied from one period and from one state, city, cult centre, and family to another. Adherence to alternative versions reflected not only local traditions but also rivalries, factionalism, and resistance to centralization. Rationalized corpuses of mythology were developed for literary purposes only after myths had ceased to have major religious and political significance. Much of the seeming unity of modern versions of Greek and Roman myths is the product of harmonization that occurred during the Renaissance (Grant 1973). To compare concepts relating to cosmology and cosmogony in different early civilizations, it is necessary to focus not on the surface detail but on the basic structures of myths.