《吕氏春秋·纪·孟春纪》
让乌获这样的大力士去拉住牛的尾巴，即使尾巴拽断了，人的力气用完了，牛还是不走，这是由于它违背了牛的性子。
使乌获疾引牛尾，尾绝力勯，而牛不可行，逆也。
Let a strongman like Wuhua pull the tail of a cow, even if the tail is broken, and the man's strength is exhausted, the cow still does not move because it goes against the cow's nature. 