During the Spring and Autumn period, after Duke Xiang of Lu died, the three powerful ministers—Jisun, Shusun, and Mengshu—placed Prince Chou on the throne, later known as Duke Zhao of Lu.
Duke Zhao of Lu was a pleasure-seeking ruler who cared only for feasting and amusement, leaving state affairs in chaos as power fell into the hands of the three noble families—Jisun, Shusun, and Mengsun—with Jisun holding the greatest influence.
In 537 BC, Ji Sun decided to divide the royal fields of Lu into four shares, taking two for himself and giving one each to Shu Sun and Meng Sun, then offering a portion of the harvest as tribute to Duke Zhao of Lu, further weakening the royal treasury.
Years later, when the mother of Duke Zhao of Lu passed away, the duke showed not a trace of grief during the mourning period—he even went hunting with his guards for amusement, further losing the people's support within the state.
However, Duke Zhao of Lu was not entirely oblivious; he sensed the threat posed by the three ministers—Jisun, Shusun, and Mengsun. So he sought out the officials Gongruo, Housun, and Zangsun, who were at odds with the three ministers, planning to eliminate them at an opportune moment.
That autumn, the opportunity finally arrived when one of the three ministers, Shusun, left the capital for personal reasons. Duke Zhao then dispatched troops to surround the residence of Jisun.
Before Ji Sun could muster his troops to counterattack, he had no choice but to fortify his mansion. However, when Shu Sun's retainers learned of the attack, they immediately led forces to rescue Ji Sun. Seeing this, Meng Sun also swiftly deployed his army, and together they routed Duke Zhao of Lu's forces, killing the commanders Gong Ruo and Hou Sun. Realizing the situation was hopeless, Duke Zhao fled with Zang Sun to seek refuge in the state of Qi.
Since Duke Zhao of Lu had long lost the people's support, his exile stirred no sympathy among them; instead, they felt a collective sense of relief, as if a heavy burden had been lifted.
Later, the idiom "as if relieved of a heavy burden" came to describe the lightness and joy one feels after being freed from a certain load.
Source: *Guliang Zhuan*, Chapter "Duke Zhao, Year 29"
Meaning of the Idiom: Later, the Chinese idiom "如释重负" came to describe how the lightness and joy one feels after being freed from a certain load.