The meaning of contradictory idioms

"Contradiction comes from Everything is Wrong, an idiom story. Caption: During the Warring States Period, there was a man selling spears and shields in Chu State. He first boasted that his shield was hard and said, "Nothing can destroy it! ""Then he boasted that his spear was so sharp that nothing could destroy it! "The hostages in the market asked him," What will happen to them if you stab your shield with your spear? "The man couldn't answer. People laughed at him. An indestructible shield and a spear without an indestructible shield cannot coexist. [1] This person has no answer. Later, he acted according to the description or acted differently from his words and deeds. It also refers to a disjointed character or mood. The language "Everything is done by Nan Yi": "The Chu people have shields and spears, saying,' My shield is strong and can't sink. "He praised his spear and said,' The benefits of my spear are all trapped in things.' Or:' What if a child's spear covers a child's shield?' He has the ability to respond. Invincible shields and invincible spears cannot coexist. "Later, I satirized those who were inconsistent in their words and deeds.