墨子怒耕柱子。耕柱子曰：“我無愈于人乎？”墨子曰：“我將上太行，以驥與牛駕，子將誰策？”耕柱子曰：“將策驥也。”墨子曰：“何故策驥也？”耕柱子曰 ：“驥足以策。” 墨子曰：“我亦以子為足以策，故怒之。”耕柱子悟。    

Mozi was angry at Gengzhuzi, his pupil. Gengzhuzi wondered, "Am I inferior to others?" Mozi asked him, "Supposed I am going up to Mt. Taiheng, carried by a good horse or an ox, which will you whip?" Gengzhizi answered, "I will certainly whip the horse." Mozi continued, "Why the horse?" Gengzhuzi said, "The good horse is worth urging on." Mozi said, "I think you are worth urging on. That is why I am angry at you." The words cast light on Gengzhuzi.