In 257 BCE, the Qin army besieged Handan, the capital of Zhao. Lord Pingyuan, Zhao's prime minister, was dispatched to Chu to negotiate a military alliance. He planned to bring twenty elite warriors, but after careful selection, he was still one short. Then a retainer named Mao Sui stepped forward and volunteered himself. Lord Pingyuan, having no memory of him, questioned Mao Sui thoroughly before reluctantly agreeing to let him join.
Mao Sui, unremarkable in appearance and unassuming in speech, was actually a man of sharp wit and eloquence. Upon arriving in the state of Chu, he engaged his nineteen traveling companions in discussions on world affairs, speaking with such clarity and logic that they all marveled at his profound knowledge and persuasive skill.
On the day of the meeting between Lord Pingyuan and King Kaolie of Chu, the talks dragged from morning until noon without any resolution. The anxious retainers grew restless, so Mao Sui volunteered to go up the hall and assess the situation. Mao Sui calmly ascended the steps, hand on his sword. The King of Chu, dismissing him with contempt, ordered him to withdraw, but Mao Sui gripped his sword hilt, strode forward, and declared, "Your Majesty dares to be so rude to me in my master's presence only because you rely on the might of Chu's army. But now, with less than ten paces between us, your life is in my hands—what use are all your troops?"
Mao Sui then delivered a powerful historical analysis of Chu-Qin relations, explaining, "The Zhao delegation seeks an alliance not merely to save Zhao, but to rescue Chu from Qin's aggression."
Impressed by Mao Sui's reasoning, the King of Chu agreed, and together with Lord Pingyuan, they held a covenant ceremony, successfully sealing the alliance against Qin.
After Lord Pingyuan returned to the State of Zhao with his entourage, he spoke of Mao Sui's contributions on this trip and said with deep emotion:
“I dare not speak of recognizing talent ever again,” sighed the Zhao court official, reflecting on his failure. “I have identified thousands of capable men—at least several hundred—and believed no true genius could escape my eye. Yet I utterly failed to recognize Mao Sui’s ability. As soon as Master Mao reached the state of Chu, his words elevated Zhao’s standing above the sacred Nine Tripods. His speech before the King of Chu proved mightier than a million soldiers!”
From that day forward, Mao Sui was highly valued by Lord Pingyuan and treated as an honored guest.
Later, the idiom "Three-Inch Tongue" came to describe someone eloquent and persuasive.
Source: *Records of the Grand Historian*, "Biographies of Lord Pingyuan and Yu Qing"
Meaning of the Idiom: Later, the Chinese idiom "三寸之舌" came to describe how someone eloquent and persuasive.