During the Spring and Autumn period, Duke Zhuang of Qi was once riding in his chariot to hunt in the outskirts. As the chariot moved along, the sharp-eyed duke spotted a small insect on the road that, instead of dodging the oncoming wheel, raised its two front legs and bravely charged straight at the massive wheel.
Duke Zhuang of Qi found it very strange, immediately ordered the driver to stop the carriage, and pointing at the insect asked, "What kind of insect is this?" The driver looked and said, "Your Majesty, this is a mantis." Duke Zhuang of Qi then asked, "Why does it charge forward recklessly, doesn't it know the wheel will crush it to death?"
The charioteer said, "Your Majesty, though this insect is small, it only knows to advance, not retreat. It completely overestimates its own strength and recklessly acts without regard for consequences. Look, it's still brandishing its claws, trying to block our chariot from moving forward."
Duke Zhuang of Qi sighed, "If this were a man, he would surely be a warrior renowned throughout the land!"
So the Duke ordered his charioteer to pull the carriage aside, allowing the mantis to pass. When word of this spread, many warriors, believing Duke Zhuang of Qi had an eye for talent, came to pledge their allegiance to him.
Another tale of a mantis trying to stop a chariot also dates back to the Spring and Autumn Period.
During the late Spring and Autumn period, Duke Ling of Wei heard that the renowned scholar Yan He, who was traveling through the state, possessed great talent and learning. The duke planned to appoint him as tutor to his heir, Prince Kuai Kui. Yan He had long heard of the prince's notorious reputation—brutal, quick to kill, and deeply feared by the people. Troubled, Yan He visited the sage Qu Boyu of Wei to seek advice. "I have been summoned to teach the prince," Yan He explained. "But if I indulge his cruelty, I will harm the state; if I correct him, I risk my own life. What should I do?" Qu Boyu replied, "Your concern is wise. Be cautious: outwardly go along with him, but inwardly maintain your integrity. Do not try to force change—that only invites disaster. Like a driver who steers a wild horse, you must guide gently or be thrown." Yan He heeded this counsel, and the story became a classic lesson in navigating dangerous power with subtle wisdom.
Yan He asked Qu Boyu, "I've heard that Kuai Kui is stubborn and violent, treating murder like a game. Now the king wants me to be his tutor. I'm torn: if I let him run wild, he'll harm the state and cause chaos; but if I rein him in, he'll turn on me. What should I do?"
Qu Boyu warned that trying to educate the unruly heir Kuaikui with talent would be extremely difficult. He advised that as Kuaikui's tutor, one must act with utmost caution and never provoke the prince, or risk deadly consequences. He illustrated with a metaphor: a man who loved his horse so much that when he saw a bug biting it, he slapped the horse, only to have it bolt in panic, throwing and trampling him to death. Then Qu Boyu added another example: "Do you know the mantis? Once, while riding in my carriage, I saw a mantis on the road. It clearly saw my chariot approaching but defiantly raised its forelegs, trying to block my wheels. It didn't realize its own power was utterly insufficient, and was crushed to pieces under the wheels!"
Finally, Qu Boyu warned Yan He, "The mantis is crushed because it overestimates its own strength. Learn from this and act with caution. If you also overestimate yourself and try to change the cruel nature of Kuai Kui, it would be like provoking this prince—your fate will be no different from the mantis, ending in utter ruin!"
Impressed by Qu Boyu's wisdom, Yan He decided not to provoke Kuai Kui and quickly returned to the State of Wei. Later, Kuai Kui indeed stirred up more trouble and was killed.
Both stories use "a mantis trying to stop a chariot" to illustrate a principle. "Tang" is the mantis, "bi" is its forelegs, and "dang" means to block. Later, it became an idiom describing someone overestimating their strength and courting inevitable failure, carrying a negative connotation.
Source: *Han Shi Wai Zhuan*
Meaning of the Idiom: Later, the Chinese idiom "螳臂当车" came to describe how someone overestimates their strength and courts inevitable failure.