" Yin-yang is a sort of force,’ said Xiang-yun. ‘It’s the force in things that gives them their distinctive forms. For example, the sky is Yang and the earth is Yin; water is Yin and fire is Yang; the sun is Yang and the moon is Yin. "

― Cao Xueqin , The Story of the Stone, or The Dream of the Red Chamber, Vol. 2: The Crab-Flower Club