自相矛盾～英译

A man from the state of Chu was selling a spear and a shield in a busy market. To the onlookers, he first bragged about his shield: "my shield is so strong that nothing sharp can pierce it!" After a while, he took up his spear and boasted, "my spear is so sharp that anything strong can be pierced!" The crowd laughed at what he said. Someone asked him, "what would happen if you used your spear to pierce your shield?" The man was so tongue-tied that he could not answer the question. He had to put away his spear and shield and left the downtown area in disgrace.