Yi Fa Qian Jun – A Hair’s Weight of a Thousand Jins

Idiom Story: Mei Cheng, courtesy name Shu, was from Huaiyin (modern-day Jiangsu province) and was a renowned fu (rhapsody) writer in the early Western Han Dynasty. Among his nine known compositions, only three, including Seven Stimuli, have survived. His works were once compiled but are now mostly lost, with contemporary scholars reconstructing his works into The Collected Works of Mei Shu.

Initially, Mei Cheng served as a literary attendant in the court of King Liu Pi of Wu. In 154 BC, Liu Pi, along with King Liu Wu of Chu, King Liu Ang of Jiaoxi, King Liu Xiongqu of Jiaodong, King Liu Xian of Zichuan, King Liu Piguang of Jinan, and King Liu Sui of Zhao, raised an army in rebellion under the pretext of “purging the court.” This rebellion is known as the Rebellion of the Seven States. Emperor Jing dispatched generals Zhou Yafu and Dou Ying to quell the rebellion. After three months, the rebel forces were defeated. Liu Pi fled to Dantu and was killed, while the other six kings either surrendered or committed suicide.

Liu Pi was the son of Liu Zhong, who was the elder brother of Emperor Gaozu of Han. Liu Zhong was made King of Dai in 200 BC, but later, the Xiongnu invaded the Dai region, and Liu Zhong fled, losing his title and being demoted to Marquis of Taiyang. In 196 BC, Ying Bu, the King of Huainan, rebelled, killed King Liu Jia of Jing, and forced Liu Zhong to flee. Emperor Gaozu, despite being ill, personally led an army to suppress the rebellion. Liu Pi, then twenty years old and known for his strength, served as a cavalry officer and played a key role in the victory against Ying Bu’s forces. As Liu Jia had no heirs, Emperor Gaozu, worried about the Jing region’s defense, decided to make Liu Pi King of Wu, governing three commanderies and fifty-three cities. Despite reservations about Liu Pi’s rebellious nature, Emperor Gaozu hoped Liu Pi would remain loyal.

From the time of Emperor Hui and Empress Lü, Liu Pi harbored rebellious intentions. By the time of Emperor Wen and especially Emperor Jing, Liu Pi openly conspired with other kings to rebel, citing the central government’s policies as unfair. Mei Cheng, serving as a literary attendant to Liu Pi, noticed his intentions and wrote a Letter of Admonition to dissuade him, metaphorically describing the dangerous situation as “suspending a weight of a thousand jins by a single hair.” He warned Liu Pi of the dire consequences but was ignored. Eventually, Mei Cheng left Liu Pi and served Prince Liu Wu of Liang. The Rebellion of the Seven States was swiftly suppressed by Zhou Yafu, and Liu Pi was killed.

The phrase “suspending a weight of a thousand jins by a single hair” was later simplified and became the idiom “a hair’s weight of a thousand jins” (一发千钧), symbolizing extreme peril or a critical situation.