Lu Xiangshan, also called Lu Jiuyuan, started the idealistic trend in Chinese philosophy. He emphasized the supremacy and self-sufficiency of the mind, contrary to his contemporary Zhu Xi, who stressed the need to discover reason and to acquire knowledge of the external world. He lived in the province of Jiangsi. His father was a respected member of the gentry, and from his early youth Lu was able to devote himself to the study of Confucius and Mencius. He disagreed with the views of the scholar Cheng Yi of the Northern Sung Dynasty.

The same is true of sages born in the West, the North, and the South and of those born thousands of generations earlier and later. What he meant is...