In the late Spring and Autumn period, King Helü of Wu led troops to attack Yue, was struck by an arrow, and suffered a severe wound. On his deathbed, he told his son Fuchai, "Do not forget that Goujian killed your father!"
Two years later, King Goujian of Yue heard that King Fuchai of Wu was training his troops day and night to avenge his father, so he decided to strike first and attack Wu. Minister Fan Li advised against it, but Goujian ignored him, only to suffer a crushing defeat and flee back, trapped by Fuchai in the capital city of Kuaiji, where he had no choice but to sue for peace.
Wu Zixu, a high minister of the Wu State, strongly opposed Yue's peace negotiations. Another minister, Wen Zhong, said to Goujian, "The Wu Grand Steward Bo Pi is greedy for wealth and lustful. We can bribe him with beautiful women and gold to drive a wedge between Fuchai and Wu Zixu. Once that succeeds, Fuchai will grant our request."
After receiving beautiful women and bribes from the state of Yue, Bo Pi advised King Fuchai of Wu, "Since Goujian is willing to submit to you as a vassal, I think you should accept—it will greatly benefit Wu." Fuchai agreed to make peace with Yue, but his minister Wu Zixu warned, "Heaven itself is handing Yue to Wu on a silver platter; if you don't destroy them now, you will regret it later." Yet Fuchai refused to listen to his counsel.
Under Fan Li and Wen Zhong's guidance, King Goujian of Yue toiled tirelessly, sleeping on brushwood and tasting gall, honoring the worthy, and consoling the bereaved, transforming his weak state into a formidable power. He also exploited the corrupt minister Bo Pi to frame Wu Zixu, forcing King Fuchai of Wu to order Zixu's suicide.
In 482 BC, Fuchai was meeting with feudal lords abroad to contend for hegemony with Jin when Yue troops took advantage of his absence to attack the Wu capital. Fuchai sued for peace with Goujian. Four years later, Goujian raised an army and destroyed Wu. Fuchai committed suicide, sighing before his death, "I have no face to see Wu Zixu in the underworld!"
After King Goujian of Yue conquered and destroyed the state of Wu, he had the treacherous minister Bo Pi executed. Fan Li and Wen Zhong, both originally from the state of Chu, had helped Goujian achieve victory. Foreseeing that Goujian would eventually distrust them, Fan Li fled to the state of Qi and became a wealthy merchant. Wen Zhong, however, believing his contributions to Yue were indispensable, refused to leave with Fan Li and was ultimately forced to commit suicide by Goujian.
Later, "Laoshen Jiaosi," also written as "Kushen Jiaosi," became an idiom meaning to exhaust one's body and mind in striving for self-improvement.
Source: *Records of the Grand Historian*, "Biography of King Goujian of Yue"
Meaning of the Idiom: Later, the Chinese idiom "劳身焦思" came to describe how to exhaust one's body and mind in striving for self-improvement.