Further, on the first day of the month of Phamenoth they hold a festival, which they call Entry of Osiris into the Moon, for it is the beginning of spring. Thus they locate the power of Osiris in the moon and say that Isis, as the creative principle, has intercourse with him. For this reason they also call the moon the mother of the world and they believe her nature to be both male and female since she is filled and made pregnant by the sun while she herself in turn projects and disseminates procreative elements in the air. (Plutarch, On Isis and Osiris, 43)