Cheng Yi

Cheng Yi's system rests on a pair of terms. Li is pattern or principle, the way a thing ought to be and the reason it is as it is; qi is the psychophysical stuff that any actual thing is made of. Everything that exists has both. The li of a thing is perfect and is continuous with the li of everything else, so that in his formula there is one principle with many particularisations. Qi is what varies in clarity and density, and it is where imperfection, obstruction and bad character come from.

From this he draws the claim that made his branch of the school distinctive: the nature is principle. Human nature as such is good without qualification, and what is actually observed in a person is nature refracted through their endowment of qi. Moral cultivation is therefore not the manufacture of virtue but the clearing of an obstruction.

The practice has two halves and he insisted on both. One is the investigation of things, a phrase from the Great Learning that he read as patient and repeated study of particular matters, texts, affairs, natural things, until the pattern common to them is grasped; he explicitly denied that one could exhaust all things and said that sustained work on many eventually opens out. The other is abiding in reverence, a settled inward composure maintained in ordinary activity rather than in withdrawal.

His brother Cheng Hao had emphasised the direct apprehension of unity with all things. Cheng Yi's slower, more analytic route is the one Zhu Xi took up, and it is the reason the resulting orthodoxy is named for the two of them.

Cheng Yi worked on his commentary on the Book of Changes for much of his life and finished it late, and it takes a deliberate position on what the book is for. The hexagram is read as a situation, its six lines as positions within that situation, and the relations between lines as relations between persons in office: ruler and minister, senior and junior, the man in the wrong place at the wrong time. What the text tells you is how a person of integrity should conduct themselves in the configuration described. It does not tell you what will happen.

That reading effectively removed divination from a divination manual, and Zhu Xi, who took over almost everything else from him, would not follow him here. Zhu Xi wrote his own commentary restoring the Changes to its original use as a book of prognostication, while keeping Cheng Yi's metaphysics of principle. The two commentaries were later printed together, so that generations of examination candidates read the moral and the divinatory readings side by side.

His political career ran the other way from his influence. He was tutor to the young emperor Zhezong, and his severity in that post made enemies; when the reform faction returned to power he was stripped of office, banished to Fuzhou in 1097, and his teaching was proscribed, with his followers forbidden to study under him. He died in 1107 under that ban.

Roughly two centuries later, in 1313, the Cheng and Zhu commentaries were made the basis of the civil service examinations, and stayed there until the examinations were abolished in 1905.