Cheng Yi 1033 – 1107

Cheng Yi, with his elder brother Cheng Hao, was one of the founders of the Neo-Confucian School of Principle that would culminate in the synthesis of Zhu Xi. He served briefly as imperial tutor and was repeatedly exiled for his uncompromising criticism of court policy. His teaching, recorded in the Surviving Works of the Two Chengs, identified the principle of all things, li, with the moral order of heaven and developed an austere ethic of reverent attention as the path of self-cultivation. His thought, taken up and systematized by Zhu Xi, became the orthodox tradition of Chinese learning for the next seven centuries.

Cheng Yi was born in 1033 at Luoyang in Henan, the younger of the two Cheng brothers who, with Zhou Dunyi and Zhang Zai, founded the philosophical synthesis of the Northern Song that would become the foundation of the neo-Confucian tradition. He and his elder brother Cheng Hao were nephews of Zhang Zai's wife and studied with Zhou Dunyi as adolescents; they passed the imperial examinations together in 1057.

Cheng Yi held a series of academic and tutorial posts at the Song court, where he served briefly as imperial tutor to the boy emperor Zhezong before being driven into provincial exile by his political enemies. His writings — the commentary on the Yijing, the discourses on the Analects and the Daxue, the Yi-Luo yuanyuan lu, and the recorded conversations gathered with his brother's in the Er Cheng yishu — were edited together with his brother's by their disciple Yang Shi.

Where Cheng Hao emphasized the immediate experience of humaneness and the union of heaven and humanity, Cheng Yi developed the metaphysics of li (principle) as the structuring pattern of all things and qi (psychophysical stuff) as their material substrate, and stressed the rigorous discipline of self-cultivation through 'reverence' (jing) and 'investigation of things'. His synthesis became, through Zhu Xi a century later, the orthodoxy of imperial Confucianism in China, Korea, and Vietnam. He died in 1107.