The Yin-Yang Bagua Diagram is also called the "Tai Chi Bagua Diagram". It is one of the eight basic graphics used in the "Book of Changes", an important classic of Taoism in ancient my country that discusses the changes in all things. It is also called "Bagua", with "-" and "--" symbol. The names are: Qian, Kun, Zhen, Xun, Kan, Li, Gen and Dui, which symbolize the eight natural phenomena of heaven, earth, thunder, wind, water, fire, mountain and lake. The two hexagrams Qian and Kun occupy a particularly important position in the "Bagua".