During the Jin Dynasty, Xi Jian, the father-in-law of the legendary calligrapher Wang Xizhi, was a man of vast learning who commanded great respect.
At that time, Prince Sima Lun of Zhao, seeking to expand his influence, summoned Xi Jian to serve as his subordinate. Sensing the prince's ambition to rebel, Xi Jian feigned illness and resigned from his post.
Soon, Sima Lun indeed usurped the throne and declared himself emperor, granting high offices to all who had sided with him. But this golden age was short-lived. His brothers Sima Jiong and Sima Ying, refusing to accept his rule, raised armies and attacked each other in what became known as the infamous War of the Eight Princes. In the chaos, the imperial clan member Sima Rui fled to Jiankang (modern-day Nanjing) and reestablished the court, becoming Emperor Yuan of the Eastern Jin. Throughout this turmoil, the official Xi Jian remained fiercely loyal to the throne and was rewarded with the title of General Who Assists the State.
After Emperor Yuan ascended the throne, real power fell into the hands of General Wang Dun. Dissatisfied with the emperor's attempts to curb the Wang family's influence, Wang Dun led his troops into Jiankang and executed several of the emperor's favored ministers. Emperor Yuan died of grief and anger, and his eldest son, Sima Shao, succeeded him, historically known as Emperor Ming of Jin.
To curb Wang Dun's power, Emperor Ming appointed Xi Jian as General of Pacifying the West, stationing troops beside Wang Dun. Seeing this as a threat, Wang Dun immediately petitioned the emperor, recommending Xi Jian for the post of Imperial Secretary. Emperor Ming played along and summoned Xi Jian back to court.
Xi Jian was returning to the capital when he passed through Wang Dun's territory and went to pay his respects. Wang Dun deliberately said to him, "Back then, Man Wuqiu made a decisive choice to pledge loyalty to Empress Jia—that could be called a man of insight and talent."
Xi Jian thought, during Emperor Hui's reign, Empress Jia manipulated power and clearly used cunning schemes to plot the deposition of Crown Prince Minhuai. So he disagreed, saying, "In life, maintaining integrity is most important. Man Wuqiu aided Empress Jia in her tyranny—he is a man who lost his integrity and is not worthy of praise."
"Emperor Hui is feeble-minded and incapable, while Empress Jia holds great power. In a moment of crisis, how could one not adapt? In my view, he is still a sensible man," Wang Dun said. Xi Jian retorted, "How can a true man endure humiliation and cling to life, shamelessly facing the world?"
After failing to persuade Xi Jian to join his rebellion, Wang Dun was instead mocked and humiliated. Burning with shame and rage, he placed Xi Jian under house arrest. Though he initially wanted to kill him, Xi Jian was a high-ranking court official, so a few days later, Wang Dun had no choice but to release him.
Upon returning to the capital, Xi Jian was tasked with organizing troops to defend the imperial court. In 324 AD, when Wang Dun launched a rebellion, Xi Jian defeated him, and Wang Dun died of illness during the campaign.
Later, people used the idiom "Shameless Existence" to describe those who lose their integrity and live on with thick skin.
Source: *Book of Jin*, "Biography of Xi Jian"
Meaning of the Idiom: Later, the Chinese idiom "颜人世" came to describe those who lose their integrity and live on with thick skin.