唐代大文学家书柳宗元曾在一篇题为《敌戒》的文章中写道:“皆知敌之仇,而不知为益之尤;皆知敌之害,而不知为利之大。”意思是说,人们都知道敌人是仇人,会带来很大坏处,却不知有敌人存在还有很大好处。他举例说:“秦有六国,兢兢以强;六国既除,乃亡。” 柳宗元说的“兢兢”、“”和秦国兴衰成亡的教训,给我们 Liu Zongyuan, the great writer of the Tang Dynasty, once wrote in an article titled “The Etiquette”: “Everyone knows the enemies, but I do not know the particular interests; That is to say, people all know that enemies are enemies, which can bring great harm. However, it is still a great benefit to know that there are enemies. For example, he said: ”Qin has six countries, trembling with conscience; the six countries are both, but death.“ Liu Zongyuan said ”Jing Jing“ and ”