《新唐书·列传·卷五十七》
他曾对宰相说 ：认识自己是难事，就像作家巧匠，认为自己不错，如让更高明的人来评论，那么短处都看出来了。
尝谓宰相曰： 自知者为难。如文人巧工，自谓己长，若使达者、大匠诋诃商略，则芜辞拙迹见矣。
He once said to the prime minister: It is difficult to recognize oneself, just like a writer and a craftsman who thinks he is good, if he lets a more clever person comment, then the shortcomings can be seen.