[1] In their early years the Cheng brothers studied under Zhou Dunyi and developed the science of nature from Mencius to Zhou Dunyi in Philosophy, establishing a system of science centered on the "Divine Principle".
[4] Jiang Chenying has summarized: "Henan Erchengzi to hold respect for the study of teaching.
Its purpose to strict and respectful as scrupulous, its work began to move appearance, correct color, out of the rhetoric gas between, and pushed to the end of sex up to the sky to know the fate of the base of the work of the sage, the scholar no time and can leave.
"[5] Xiong Zhichu said: "Since Yao and Shun, the saints and sages have passed on to each other without crossing one respect.
...... Ercheng both to a respect to receive the transmission of a thousand saints, and Yichuan is especially for the main nothing suitable for the solution, and thus repeatedly invented, so that the scholars have to hold, as a transcendent into the sage.