In 265 AD, Sima Yan replaced the Wei kingdom and declared himself emperor, founding the Jin dynasty, historically known as Emperor Wu of Jin. He enfeoffed all his male relatives as princes, stationing them to guard the empire's key cities and towns.
After Emperor Wu's death, the princes fought for power, attacking each other endlessly, a period known in history as the "War of the Eight Princes."
During the Western Jin Dynasty, a man named Sun Hui served in the army of Sima Jiong, the Prince of Qi. After seizing control of the central government, Sima Jiong grew arrogant and showed little respect for the reinstated Emperor Hui of Jin. Sun Hui repeatedly urged him to change his ways, but his advice fell on deaf ears. Frustrated, Sun Hui resigned and left, unwilling to be part of a regime doomed by hubris.
In 302 AD, Prince Sima Yong of Hejian and Prince Sima Yi of Changsha joined forces to kill Sima Jiong. With Prince Sima Ying of Chengdu now ruling as regent, Sun Hui was appointed as a military advisor. Soon after, Sun Hui killed Sima Ying's gate commander Liang Jun without authorization, then changed his name and fled to escape punishment.
Later, when Sima Yue, Prince of Donghai, raised an army at Xiapi with great momentum, Sun Hui placed high hopes on him and wrote him a letter. In the letter, he praised Sima Yue's uprising as "following the righteous path to punish the rebellious, upholding justice to attack evil," comparing it to "a mountain crushing an egg," certain of victory.
Sima Yue greatly admired Sun Hui's literary talent, so he posted notices everywhere to find him, eventually locating him and appoint him as "Records Secretary." Thereafter, Sun Hui was repeatedly promoted and valued. Later, people used the idiom "Mount Tai Crushing an Egg" to describe a vast disparity in power, where the strong inevitably crushes the weak.
Source: *Book of Jin*, "Biography of Sun Hui"
Meaning of the Idiom: Later, the Chinese idiom "泰山压卵" came to describe a vast disparity in power, where the strong inevitably crushes the weak.