During the late Western Han Dynasty, the imperial relatives held sway over the court
This man was quite calculating. One year, he submitted a memorial to the emperor, proposing to imitate the Duke of Zhou by building a Mingtang hall and establishing a Yongling Tower, gathering scholars from across the empire to lecture and write books. Of course, his real aim was to elevate his own status and brand himself as the Duke of Zhou of his era.
During that time, numerous buildings were constructed for scholars and researchers, complete with essential supplies and equipment, a structured system was established, teachers with specialized expertise were appointed, and books from every field across the realm were extensively collected.
For those with special talents, official carriages from the government were sent to invite them. In this way, several thousand talented individuals were gathered here. Once they arrived, they were instructed to write books and establish theories according to Wang Mang's intentions, and to correct so-called "heresies" that were unfavorable to him.
Many court officials, fearing the imperial relatives, submitted memorials flattering Wang Mang, saying: "When the Duke of Zhou assisted the government, it took him seven years to establish the system; the Bright Hall was ruined and the Yongling Tower collapsed, and no one rebuilt them for a thousand years. Now, the Duke of Anhan has assisted Your Majesty for only four years, and his merits and virtues are already exceptionally outstanding."
Later, Wang Mang gathered over 100,000 scholars and commoners to write poems praising his virtues. After nearly twenty days of intense effort, these works were finally completed—what was called "the great task was accomplished."
After that, Wang Mang's ambition grew unchecked: first poisoning Emperor Ping of Han and proclaiming himself "Acting Emperor"; then insincerely appointing the two-year-old Liu Ying as Crown Prince; finally declaring himself emperor outright and changing the dynasty's name to "Xin."
However, Wang Mang's imperial dream was short-lived. Within a decade, the Xin Dynasty collapsed under the onslaught of peasant rebel armies like the Red Eyebrows and Green Woodsmen, and Wang Mang himself was killed when the Green Woodsmen stormed Chang'an.
"The idiom 'Da Gong Bi Cheng,' also written as 'Da Gong Gao Cheng,' means a major project or great undertaking has been completed."
Source: *Book of Han*, "Biography of Wang Mang, Part One"
Meaning of the Idiom: Later, the Chinese idiom "大功毕成" came to describe a major project or great undertaking has been completed.