This is a short article by Liu Zongyuan in Tang Dynasty, entitled Enemy Ring. Its thinking logic is completely contrary to the common sense of ordinary people and full of philosophy. This is a strange article. Liu is recognized as "everyone knows the enemy of the enemy, but they don't know that it is particularly beneficial;" Everyone knows the harm of the enemy, but they don't know the great benefits. The six countries of Qin are conscientious and powerful; The six countries will die. " It means that not having enemies is not necessarily a good thing. As the saying goes, a hero without an opponent is lonely and has no determination and fighting spirit to make progress. "Be prepared for danger in times of peace", it is the threat of the enemy that will constantly improve and expand itself. When Jin defeated Chu in Yanling, Jin Ligong felt that he had no rival and could sweep the world. Before the reunification of Qin, the threat of the six countries could make great efforts to govern the country, but once it was unified, it was blackmailed, leading to the death of II. This is what Gong Liu expressed. In fact, it has a warning function now.