During the Warring States period, Zou Ji was a strikingly handsome man in the state of Qi
One day, Zou Ji gazed at himself in a mirror, eager to know how he compared to the famed handsome man Xu Gong. He asked his wife, "Between Xu Gong and me, who is more handsome?" Without hesitation, she replied, "Of course it's you—Xu Gong can't compare." Doubtful, Zou Ji then asked his concubine, "Who is more beautiful, Xu Gong or me?" She timidly answered, "You are extremely handsome; how could Xu Gong match you?" The next day, a friend visited, and after chatting, Zou Ji inquired, "Do you think Xu Gong or I am better looking?" The friend, needing a favor from Zou Ji, smiled and said, "Xu Gong is not as handsome as you."
Zou Ji heard three people say he was more handsome than Lord Xu, but he remained skeptical. The very next day, Lord Xu happened to visit. Zou Ji studied him carefully and realized he was not as handsome. After Lord Xu left, Zou Ji examined himself in the mirror repeatedly, concluding that compared to Lord Xu, he was far inferior.
Zou Ji could not sleep all night, finally realizing the truth: his wife called him handsome out of partiality, his concubine out of fear, and his friend out of a favor he sought.
Zou Ji reflected that a ruler of a nation should be even less deceived by flattery, so he went to see King Wei of Qi and advised him, "Your Majesty, I have learned from my own experience that we must seek out honest criticism."
King Wei found Zou Ji's words very reasonable, so he issued an edict to his ministers: "From now on, whether officials or commoners, those who point out my faults to my face will receive top rewards; those who criticize me through written memorials will receive middle rewards; those who discuss my mistakes behind my back and I come to hear of it will receive lower rewards."
After King Wei of Qi issued his decree, ministers and officials flocked to the palace to submit memorials pointing out his faults and discussing the successes and failures of court policies, making the palace gates and halls as bustling as a marketplace.
As the governance of the court continued to improve, King Wei of Qi also steadily corrected his own faults, diligently managing the state, and thus Qi flourished and prospered.
Later, people used the idiom "Doorway Like a Marketplace" to describe a place with many visitors.
Source: *Strategies of the Warring States*, Chapter "Strategy One of Qi"
Meaning of the Idiom: Later, the Chinese idiom "门庭若市" came to describe a place with many visitors.