千钧一发 — “In a critical and precarious situation”

Han Yu, styled Tuzhi, was a renowned literati from Dengzhou, Nanyang during the Tang Dynasty. He was a leading figure who advocated for literature to convey moral principles and pioneered a literary reform that replaced parallelism with prose. His influence was profound, earning him the credit of "revitalizing literature after eight dynasties of decline."

He was a strong opponent of Buddhism. When Emperor Xianzong sent envoys to welcome Buddha relics into the court, Han Yu submitted a memorial to remonstrate against it, which offended the emperor. Consequently, he was demoted to serve as an inspector (Cishi) in Chaozhou.

In Chaozhou, he befriended an enlightened monk with whom he had much in common. As Han Yu had few friends in Chaozhou, he maintained a close relationship with this monk. Consequently, rumors spread that Han Yu had also embraced Buddhism.

His friend Meng Jiao, styled Jidao, who was then a Shangshu (Minister) and a devout Buddhist, was also demoted to Jizhou for offending Emperor Xianzong. Upon arriving in Jizhou, he heard the same rumors about Han Yu converting to Buddhism. He was somewhat perplexed, knowing Han Yu was a staunch opponent of the faith. Therefore, he wrote a letter specifically to inquire about the matter.

Upon receiving Meng Jidao's letter, Han Yu realized that his interactions with the monk had led to misunderstandings. He immediately wrote back to clarify. Furthermore, Han Yu vehemently criticized the ministers at court who, he believed, had abandoned Confucianism for Buddhism, using superstition to delude the emperor. He was indignant that the emperor distanced himself from virtuous people and allowed Confucian principles to decline.

In his letter, Han Yu wrote: "With a hundred holes and a thousand wounds, things are lost with every disturbance, all precarious as a single hair pulling a thousand jun..." This phrase metaphorically describes a situation reaching an extremely dangerous point, like a thousand jun (an ancient unit of weight) hanging by a single strand of hair. Today, people often use this idiom to describe any dire or critical situation. This idiom is found in Han Yu's "Letter to Minister Meng," which contains the line: "all precarious as a single hair pulling a thousand jun, prolonged and gradual, dwindling to nothing."