A man who observes will have no disciples, and a clear water will have no fish. It means that if the water is too clear, the fish can't survive, and if you are too strict with others, there will be no partners. Now it is sometimes used to mean not to ask too much of people or things.

The original source: Zhang Wen, the son of "Da Dai Li Ji", entered the official article 65:

Therefore, a gentleman should not be ignorant of the nature of the people and reach the feelings of the people; It is known that he has learned from life, and then the people are obedient. If the deceased is a pro-citizen, the people will have no complaints if the government is equal. Therefore, when a gentleman reaches out to the people, he doesn't want to be high, he doesn't want to be far, and he doesn't blame the people for what they can't do. The success of the Ming king in the present, but the people are strict and don't meet it; After several years of industry, the people will be ill, and the sick will be cured. Therefore, the ancient people crowned and looked forward, so they covered the Ming dynasty; It's all about the ear, so it's smart. Therefore, there is no fish when the water is clear, and there is no disciple when people observe it.

Therefore, a learned and virtuous person, when governing the people, can not help but know the nature of the people, can not help but understand the psychology of the people, know their innate reason and acquired habits, and the people can completely obey your decree. Therefore, if the country is well governed, the people will love you; Politics is clear and peaceful, and the people naturally have no resentment. Therefore, a learned and virtuous person should not set too high an ideal or set too far a goal when governing the people, and should not ask the people to do things that they cannot do. If you use the ancient sage's ideal of success to ask the people to achieve it immediately, I'm afraid the people will stay away from it and dare not welcome it. You tell them the long-term future goal, the people are suffering, and when they are suffering, they should avoid it. Therefore, in ancient times, a string of jade hung on the crown of the emperor, just to be alert to himself, and not to see it too clearly; Plug your ears with cotton wool to be alert to yourself, and don't listen too carefully. So if the water is too clear, no fish can survive; If you are too smart, no one will be your partner.