Yin and yang are a pair of sides that stand opposed and yet complete each other, and the Five Elements are five material agents that both generate and overcome one another. Seen within these two sets of relations, change in all things has an order that can be explained.
In the second year of King You of Zhou (780 BCE) an earthquake struck the Three Rivers, and the scribe Boyang Fu explained it as yang trapped and unable to rise, pressed down by yin (Discourses of the States, Discourses of Zhou).
In the Warring States period, Zou Yan of Qi joined the Five Elements to yin-yang and created the theory of the cycle of the five virtues.
In the Western Han, Dong Zhongshu's Luxuriant Dew of the Spring and Autumn Annals built a system of correspondence between heaven and man on yin-yang and the Five Elements.
Yin-yang and the Five Elements is the class in the chapter on the Cosmos on a body of thought, from the Zhou onward, for explaining change in nature. Yin and yang describe two opposite sides that complete each other, and the Five Elements describe five material agents that generate and overcome one another. From Boyang Fu in the time of King You of Zhou to Zou Yan in the Warring States and Dong Zhongshu in the Western Han, people used it to explain how heaven, earth and all things change.
