In a universe animated by the interaction of yin (female) and yang (male) energies, the moon was literally yin visible. Indeed, it was the very germ or source of yin, and the sun was its yang counterpart.
Li BaiBears, dragons, tempestuous on mountain and river, Startle the forest and make the heights tremble. Clouds darken beneath the darkness of rain, streams pale with a pallor of mist. The gods of Thunder and Lightning Shatter the whole range.
Li Bai