《后汉书·列传·逸民列传》
后来朝廷用诏书召逢萌，萌托以年太老，迷失道路的东西方向，并对使者说 ：朝廷召我的原因，以为我对政治有益处，我连方向都不知道，怎能济时呢？ 
后诏书征萌，托以老耄，迷路东西，语使者云： 朝廷所以征我者，以其有益于政，尚不知方面所在，安能济时乎？ 
Later, the court sent an imperial edict to summon Feng Meng, but Meng claimed that he was too old and had lost his sense of direction, and said to the messenger: "The reason the court summoned me is because they thought I could be useful in politics. I don't even know my own direction, so how can I help the times?" 