Who is Guan Yinzi 关尹子？

Guan Yinzi was one of the top ten outstanding figures in the pre-Qin period. He served as a court official, a general, a philosopher, and an educator in the Zhou Dynasty. He was an important Taoist figure among the various pre-Qin philosophical schools, the founder of the Louguan School and the Wenshi School of Taoism. With the courtesy name Gongwen and the given name Xi, he once served as the Guanling (the official in charge of the pass). 

He lived in the same era as Laozi. The five-thousand-character Tao Te Ching written by Laozi was composed at his request. Liu Xiang said, "Xi wrote a total of nine essays, which were named Guan Yinzi." The Book of Han: Yiwenzhi recorded nine essays of Guan Yinzi, which were traditionally titled as written by Yin Xi of the Zhou Dynasty. That is what is known as the Zhenjing of Wenshi in later generations. He should have written this book after Laozi's Tao Te Ching, and his Taoist ideas were also quite similar. Therefore, in Zhuangzi: Tianxia, when describing the ancient Taoist techniques, Laozi and Guan Yinzi were mentioned together. The main essence of his thought lies in valuing the origin and emphasizing the spirit, being indifferent and inactive, maintaining purity and tranquility, relying solely on the concept of nothingness, and responding according to the nature of things. Guan Yinzi's thought of valuing purity had an important influence on the formation of the Chinese concept of "purity".