Joseph Campbell in The Power of Myth, a 1988 interview with Bill Moyers, links the image of the Earth or Mother Goddess to symbols of fertility and reproduction. For example, Campbell states that, "There have been systems of religion where the mother is the prime parent, the source... We talk of Mother Earth. And in Egypt you have the Mother Heavens, the Goddess Nut, who is represented as the whole heavenly sphere". Campbell continues by stating that the correlation between fertility and the Goddess found its roots in agriculture.
Bill Moyers: But what happened along the way to this reverence that in primitive societies was directed to the Goddess figure, the Great Goddess, the mother earth- what happened to that?
Joseph Campbell: Well that was associated primarily with agriculture and the agricultural societies. It has to do with the earth. The human woman gives birth just as the earth gives birth to the plants...so woman magic and earth magic are the same. They are related. And the personification of the energy that gives birth to forms and nourishes forms is properly female. It is in the agricultural world of ancient Mesopotamia, the Egyptian Nile, and in the earlier planting-culture systems that the Goddess is the dominant mythic form.
Campbell also argues that the image of the Virgin Mary was derived from the image of Isis and her child Horus: "The antique model for the Madonna, is Isis with Horus at her breast".