Nan Yi, Han Feizi: There was a man in Chu who sold both shields and spears in the market. In order to attract customers and sell his goods as soon as possible, he did not hesitate to exaggerate and exaggerate loudly. First, he raised the shield in his hand and boasted to passers-by: "Ladies and gentlemen, please look at this shield in my hand. It is a good shield forged with good materials at one time, with a particularly strong texture. No sharp spear can penetrate! " These words made people gather around and watch carefully. Then, the Chu people picked up the spear against the wall and boasted more brazenly: "Heroes, please look at this spear in my hand again. It's a good spear hammered out, with a particularly sharp point. No matter how strong your shield is, it will be pierced by my spear! " When this big talk came out, everyone who listened was dumbfounded. After a while, I saw a man stand out from the crowd, pointing to the Chu people and asking, "You just said that your shield is so strong that no spear can pierce it;" Your spear is so sharp that no shield can resist it. Then ask: What if I poke your shield with your spear? "The Truman was speechless, so he blushed. He quickly packed up his spear and shield and fled the market despondently. Now you can't use this word to prove what you said. For example, "what you just said is inconsistent, and others don't know how to understand it." "