Cang Gong, whose surname was Chunyu and given name Yi, hailed from Linzi in Qi (modern-day Zibo, Shandong). Having served as the magistrate of the Grand Granary, he earned the title "Cang Gong" and was a renowned physician of the early Han Dynasty.
Chunyu Yi had loved medicine since childhood and studied under Yang Qing, mastering the healing arts passed down from the Yellow Emperor and Bian Que, curing many difficult and complex diseases. However, after offending a powerful noble, he was sentenced to corporal punishment—including tattooing the face, cutting off the nose, or amputating the feet—and was to be taken to Chang'an for execution. Chunyu Yi had only five daughters and no sons. As he faced his weeping daughters before departing, he sighed, "I have no sons, no one to rely on in a crisis!"
"I only have daughters, no sons—when it comes to a crisis, none of them can be of any use!"
His young daughter Tiying was deeply saddened and decided to follow her father west to Chang'an, where she wrote a letter to Emperor Wen of Han. The letter read:
“When my father served as an official, the people of Qi all praised him for his integrity and fairness. Now that he has committed a crime, he certainly deserves punishment. But I deeply feel that once a person dies, they cannot be brought back to life, and once a limb is severed by corporal punishment, it cannot grow back. Even if he wishes to reform and start anew, it would be impossible. I am willing to become a government slave to atone for my father’s crime, so that he may have a chance to change his ways and begin again.”
After reading Ti Ying's letter, Emperor Wen of Han was deeply moved. He not only pardoned Chunyu Yi's crime but also felt that corporal punishment was too cruel, so he issued an order abolishing it.
Later, people derived the idiom "Repent and Reform" from this story, meaning to correct one's mistakes and start anew.
Source: *Records of the Grand Historian*, "Biographies of Bian Que and the Duke of Cang"
Meaning of the Idiom: Later, the Chinese idiom "悔过自新" came to describe how to correct one's mistakes and start anew.