What does the joke of Confucius' seventy-two students who has the richest money mean?

At the suggestion of Confucius, his disciple Gong Xichi is going to send an envoy to Qi. Considering that after I left, my mother at home didn't think so.

Health; The teacher helped him a lot, and he could no longer speak. Gong Xichi entrusted his younger brother and You Ran, the housekeeper of Confucius, to ask the teacher for some food for his mother to eat after he left. Confucius listened to You Ran's request and said, "Then give her a pot full of millet seeds (pot, the ancient unit of measurement, a pot is about six and a half buckets today)." "Gong Xichi will go for a long time. Teacher, do you think you can give her more? " "Then add another Yu to her (Yu is also an ancient unit of measurement, and one Yu is equivalent to more than two fights today)." You Ran wanted to say more, but Confucius turned his head to one side and closed his eyes.

Ran has quit, thinking: the teacher is a bit too stingy. When Gong Xichi left, he wouldn't pay it back for three or two years. The little millet you gave him will last for a few days, and then he won't starve people to death. So, he offered 80 stones of millet. Confucius later learned about it. He neither doubted Ran's selfish behavior, nor criticized him for acting on his own initiative. Instead, he said earnestly: "Gong Xichi went to Qi this time, sitting in a fat carriage, wearing warm fur, elegant." This is a heavy job. After he takes office, he is sure to make his mother live a happy life. Our family does have a lot of food, but good steel should be used on the cutting edge. Those foods are used to help people in urgent need, not to add wealth to the rich. When Gong Xichi received her salary and sent it home, the dozens of stones left by her mother became worthless in her eyes. And if we use these dozens of stones to help the poor, how many people will benefit from it? " After listening to the teacher's teaching, Ran once again felt deeply: in his own mind, there are only teachers and friends, but in the eyes of the teacher, he sees people all over the world!