The Neo-Confucianism Zhu Xi systematised in the twelfth century was the official doctrine of the examination curriculum in Ming China: everything has its *li*, its principle, and knowledge is obtained from outside through the 'investigation of things' (gewu) — the study of the classics and of the world. As a young man Wang Yangming took this seriously, investigated a bamboo plant for seven days, found no principle and fell ill.

The turning point came in 1508, when he was exiled to a remote postal station in Guizhou for objecting to corruption at court. There, in a realisation one night, he concluded that principle lies not outside but in the mind itself: *xin ji li*, mind is principle. Two teachings follow. The first is *liangzhi*: an innate moral intuition in every person that distinguishes right from wrong; education does not create it but removes what obstructs it. The second is *zhixing heyi*, the unity of knowing and acting. To know something truly is to act on it; a person who 'knows' the good and does not do it does not actually know. The gap between knowledge and conduct is not moral weakness but a deficiency of knowledge.

Wang was also a successful general and administrator, and his teaching's emphasis on action is consistent with that life. In China his influence opened a strand alternative to the official doctrine; his deepest effect, however, was in Japan, where the school known as Ōyōmei-gaku became one of the intellectual sources of the samurai generation that prepared the Meiji Restoration in the nineteenth century. In twentieth-century China both nationalist and reformist thinkers drew on him. The idea of the unity of knowing and acting is still cited today in debates in virtue ethics and the philosophy of education.