The Shield or the Sword? 自相矛盾

The Chinese expression 自相矛盾 is a very popular idiom. It is commonly used to describe situations wher people contradict themselves or their behaviour contradicts their stated beliefs. It literally means attacking one's shield with one's own spear and comes from a 2,000 year old story about a spear and shield salesman in the State of Chu.

One day the man was marketing his wares to the gathered crowd. He claimed that his spears and shields were the best in the land. In one breathe, he claimed his shields were so strong that nothing could ever penetrate them and, then in the next breathe, he said his spears were so sharp that nothing could withstand them. After listening to the seller's pitch, a man in the crowd stepped forward and said:

You just told us that your shields are the strongest in the world and that your spears are the sharpest. What happens if you use your spears on your shields?

The seller was dumbstruck and could not explain away the contradiction.

The idiomatic expression, tie oneself up in knots, expresses a similar sentiment in English.