The disciple Zeng said, “The doctrine of our master is to be true to the principles of our nature and the benevolent exercise of them to others, this and nothing more.”
曾子曰：“夫子之道，忠恕而已矣。”
Source: The Analects, Li Ren IV, Chapter 15
Author: The Disciple Zengzi / 曾子 (Regarding Confucius)
