Zou Yan 鄒衍 (ca. 305-240 BCE), also written 騶衍 or 鄹衍, was an important philosopher of the Warring States period 戰國 (5th cent.-221 BCE). He was the main representant of the school of Yin-Yang thinkers 陰陽 that investigated the relation between the cosm (macrocosm) and the human world (microcosm).
Zou Yan hailed from the state of Qi 齊, but he wandered around and found disciples in Han 韓, Yan 燕 and Zhao 趙. He was famous for his disputative talent, but also for his belief in the traditional rites that were the only means to hold together the state system of the Zhou empire 周 (11th cent.-221 BCE).
In his later years, he was sent by the duke of Qi to the state of Zhao, where he met the famous dialectician Gongsun Long 公孫龍.
Zou's philosophy explained the influence of the natural forces of Yin 陰 (dark, moon, winter) and Yang 陽 (bright, sun, summer) and of the Five Processes or Phases (wuxing 五行, wude 五德 "five forces") on human life and the life of states. He developed the theory of the successive production of the Five Phases (xiangsheng 相生) out from each other. According to this theory, there is a constant, yet spontaneous change of these five cosmic forces that determine all occurrences on earch and even influence the rise and fall of dynasties.
He also compiled the text Yueling 月令, which is today a chapter of the Classic Liji 禮記. The Yueling describes the relationship between seasons, months, astronomy, colours, music, and many other aspects of human life. The whole cosm is embedded into a system of correlations.
Zou is also credited with the authorship of a text called "Twelve Records" Shierji 十二記.
The philosophy of Zou Yan had a deep impace on cosmological thinking of the Han period 漢 (206 BCE-220 CE) and also influenced Han period Confucianism, as can best be seen in the writings of Dong Zhongshu 董仲舒, who combined the social and political thought of Confucius with Zou Yan's correlative thinking.
The imperial bibliography Yiwenzhi 藝文志 in the official dynastic history Hanshu 漢書 includes two books written by Zou Yan, the 49 chapters long Zouzi 鄒子, and the 56-chapters long Zouzi zhongshi 鄒子終始. Both were lost at an early point of time.