"Ex nihilo nihil fit" means that nothing comes from nothing. In ancient creation myths the universe is formed from eternal formless matter, namely the dark and still primordial ocean of chaos. In Sumerian myth this cosmic ocean is personified as the goddess Nammu "who gave birth to heaven and earth" and had existed forever; in the Babylonian creation epic Enuma Elish pre-existent chaos is made up of fresh-water Apsu and salt-water Tiamat, and from Tiamat the god Marduk created Heaven and Earth; in Egyptian creation myths a pre-existent watery chaos personified as the god Nun and associated with darkness, gave birth to the primeval hill (or in some versions a primeval lotus flower, or in others a celestial cow); and in Greek traditions the ultimate origin of the universe, depending on the source, is sometimes Okeanos (a river that circles the Earth), Night, or water.