Liu Nanyuan, a state official, retired to his hometown. There was an emissary named Zhi Zhi, who was very strict with his subordinate officials in terms of diet, and all the counties were afraid. Gong said, "This is my student. I should enlighten him and let him know. " When he comes, treat him well and say, "I'm going to eat, for fear of interfering with your official business." I specially reserved this bowl of rice for you. " But my wife, she went out of town and no one cooked. Can we have home-cooked meals? "Because of the teacher's orders, I dare not refuse. I haven't eaten my meal from morning till noon, and I feel very hungry. When the rice was served, there was only a bowl of rice and tofu. He ate three bowls each, pointing out that he felt full. After a while, delicious food and wine were placed in front of him, and he ate all the people. Gong insisted that he eat, and he said, "I'm full. I can't eat." Gong smiled and said, "You can know that the diet is neither refined nor coarse. It's easy to eat when you're hungry, but bad when you're full. This is only caused by time. "With this lesson, I never dare to blame others for my diet.