《淮南子·汜论训》
所以普通的铸剑工匠都因宝剑像莫邪宝剑而感到困惑，而只有欧冶这样的工匠才能识别出它们的不同种类；普通的玉工又常将一般的玉当成碧庐美玉，而只有专家猗顿才能不混淆它们之间的差别；同样，昏庸的君主也常常把伪装成君子的小人奸臣当成君子，而只有英明的君主才能不被蒙骗，并能从细微的迹象中看清真相。
故剑工惑剑之似莫邪者，唯欧冶能名其种；玉工眩玉之似碧卢者，唯猗顿不失其情；暗主乱于奸臣小人之疑君子者，唯圣人能见微以知明。
Therefore, ordinary swordsmiths are confused because the treasured sword is like the Mo邪 treasured sword, and only craftsmen like Ou Ye can recognize their different types; ordinary jade craftsmen often use ordinary jade as Bilu jade, but only experts Yidun can Distinguish between their differences, in the same way, incompetent monarchs often regard treacherous ministers who pretend to be gentlemen as gentlemen, and only wise monarchs will not be deceived and can see the truth from subtle signs.