Han Yu, the renowned Tang Dynasty writer, was orphaned as a child and raised by his sister-in-law. Through self-discipline and voracious reading, he built a solid scholarly foundation. At 35, he entered the capital as a professor at the Imperial Academy, later rising to Vice Minister of Justice.
During the Tang Dynasty, Buddhism was so popular that even Emperor Xianzong was a devout follower. When he heard that a temple housed a relic of the Buddha's finger bone, he planned a grand procession to bring it into the palace for worship. The scholar-official Han Yu strongly opposed this and wrote a memorial titled "On the Buddha's Bone," arguing, "Since Buddhism entered China, emperors have reigned only briefly; those who seek blessings from Buddha often meet tragic ends."
Emperor Xianzong of the Tang Dynasty was furious when he read Han Yu's memorial, believing the scholar was not only deliberately opposing him but also using historical references to imply the emperor wouldn't live long. The emperor ordered Han Yu's execution, but thanks to the prime minister's intercession, the sentence was commuted to demotion and exile as the prefectural governor of Chaozhou.
During the mid-Tang Dynasty, central authority was weakening. After Emperor Xianzong took the throne, he reformed some of the previous dynasty's corrupt practices, strengthening the central government's control. The poet and official Han Yu, who had been exiled to Chaozhou, seized this opportunity to submit a memorial titled "Thanks for the Appointment as Prefect of Chaozhou," in which he lavishly praised Emperor Xianzong's virtues, hoping to regain the emperor's trust and be recalled to the capital.
In this memorial, Han Yu flattered Emperor Xianzong as a pivotal ruler who could turn the tide of history, and suggested that the emperor perform the grand Fengshan ceremony on Mount Tai. Fengshan was a major ritual to worship heaven and earth; the ancients believed Mount Tai was the highest of the Five Sacred Mountains—ascending its summit to build an altar and offer sacrifices to heaven was called "Feng," while clearing a site on Mount Liangfu to the south for earth sacrifices was called "Shan." Famous emperors like Qin Shi Huang and Emperor Wu of Han had both conducted this ceremony. By making this suggestion, Han Yu was placing Emperor Xianzong among the ranks of these illustrious monarchs.
Han Yu subtly hinted in this memorial that he hoped Emperor Xianzong would allow him to participate in the grand Fengshan ceremony, adding that if he missed this once-in-a-millennium event, it would be a lifelong regret.
Later, Emperor Xianzong recalled Han Yu to the capital and appointed him as Vice Minister of Personnel, the deputy head of the office overseeing the promotion, demotion, and transfer of all officials nationwide.
"The idiom 'a once-in-a-millennium opportunity' means something that occurs only once in a thousand years, describing an extremely rare chance."
Source: *Complete Works of Han Changli*
Meaning of the Idiom: Later, the Chinese idiom "千载难逢" came to describe a once-in-a-millennium opportunity means something that occurs only once in a thousand years, describing an extremely rare chance.