《颜氏家训·兄弟篇》
譬如住的房屋，出现了一个漏洞就立刻堵上，出现了一条细缝就马上填补，那就不会有倒塌的危险；假如有了乌鹊、老鼠也不忧虑，不提防风雨的侵蚀，就会墙倒柱摧，无从挽回。
譬犹居室，一穴则塞之，一隙则涂之，则无颓毁之虑；如雀鼠之不恤，风雨之不防，壁陷楹沦，无可救矣。
For instance, when a hole appears in a house, it is immediately plugged up; when a crack appears, it is immediately filled, and it will not be in danger of collapsing; if there are magpies or mice, one does not worry about them, if one does not take precautions against wind and rain, the walls will collapse and the pillars will be destroyed, and there will be no way to recover.