A countryman from the state of Lu sent to king Song Yuangong two knots that were difficult to untie¹. The king posted a notice to find people with wisdom to undo² the knots, but nobody could undo them. Later one of Er Shou's students untied³ one of them but could not undo the other one. The student thereupon claimed, "The knot could impossibly be untied." The king sent people to check what he said with the countryman from Lu. The man from Lu said, "He is right. This knot cannot be untied. It was not him that tied this knot. And he can tell that this knot cannot be untied. He surely is more clever than I am." 鲁国的一个乡下人送给宋元公两个难以解开的连环结。 宋元公张榜招贤，却无人能够解开。 儿说一个学生解开了其中的一个，另一个怎么也解不开。这个学生于是断言：“这个绳结根本就不可能解开!”宋元公派人去问连环节的鲁国人这话是否准确。 鲁国人回答说：“的确是这样。这个结本来就是一个解不开的死结，我打这个结时，就知道它不可能被解开。说这话的人并没有亲手打这个结，却能看出这是个死结，这人的确比我聪明。”