1、【成语来源】 to contradict oneself自相矛盾AmanofthestateofChu(chǔguó楚国)hadaspearandashieldforsale. 楚国有个卖兵器的人,在市场上卖矛和盾。Hewasloudinpraisesofhisshield."Myshieldissostrongthatnothingcanpierceitthrough."为了让人家愿意买他的货,他先举起盾向人们夸口道:“你们看,我的盾是世上最坚固的盾,任何锋利的东西都不能刺穿它。”Healsosangpraisesofhisspear."Myspearissostron