Yan Zun was a Daoist and hermit at the end of the Western Han dynasty. The Gist of Lao Zi which he authored was a representative work at the time when the Daoist philosophy was undergoing significant changes. Yan inherited the theories of Lao Zi, Zhuang Zi, Heshang Gong and Huainan Zi. He mixed together elements of the Book of Changes and the Lao zi and further developed the Daoist philosophy. He made a strenuous effort to restructure the new system of the Daoist philosophy on the world view, political view, and the outlook on life. His findings produced a significant effect on the thinking of Yang Xiong and Wang Chong and the philosophical sects in the Wei and Jin dynasties.