自相矛盾：矛和盾能同时存在吗？

A seller had spears and shields. 一个卖兵器的人带着矛和盾。 He said his shields were too strong. 他夸自己的盾最结实。 Nothing could pierce them. 什么东西都刺不穿它。 Then he said his spears were too sharp. 接着，他又夸自己的矛最锋利。 Nothing could stop them. 什么东西都挡不住它。 Someone asked, what if spear meets shield. 有人问，那矛碰到盾会怎样。 The man could not answer. 这个人一下子答不上来了。