During the Spring and Autumn period, King Ling of Chu destroyed the northern state of Cai and appointed his younger brother Qiji as its governor, titled the Duke of Cai. Continuing his campaign, King Ling attacked the eastern state of Jie. Ambitious and urged by the treacherous minister Chao Wu, Qiji suddenly returned to Chu and killed King Ling's two sons. Since Qiji still had two elder brothers, he dared not seize the throne immediately; instead, he installed his nephew Ziwu as ruler and Zizhe as prime minister. When King Ling learned of this, he hanged himself in rage. After confirming the king's death, Qiji followed Chao Wu's scheme, forced Ziwu to commit suicide, and declared himself king—known historically as King Ping of Chu.
During the Spring and Autumn period, a similar tragedy unfolded in the state of Jin. The foolish Duke Xian of Jin was deeply infatuated with his beautiful concubine Li Ji, whom he made his wife, and planned to make her son Xi Qi the crown prince. Li Ji outwardly pretended to be virtuous, but secretly schemed against the original heir, Prince Shensheng. One day, Li Ji tricked Shensheng into offering a sacrifice to his deceased mother, then had poison placed in the sacrificial meat. Just as Duke Xian was about to taste the meat, Li Ji stopped him, and instead threw it to a dog, which died instantly. Li Ji then wailed loudly, accusing Shensheng of plotting to murder the duke, and sowed discord between the duke and his other sons, Chong'er and Yiwu. Believing her lies, Duke Xian ordered Shensheng to commit suicide, and sent troops to arrest Chong'er and Yiwu, who both fled the state. Chong'er eventually returned to become Duke Wen of Jin, one of the Five Hegemons of the Spring and Autumn period.
*Huainanzi*, "Forest of Sayings" commentary: "Such fratricide and filicide is as foolish as cutting off a foot to fit a shoe, or shaving the head to fit a hat."
"Cutting the feet to fit the shoes" originally meant siblings harming each other; now it describes forcing oneself to accommodate unreasonable things. It metaphorically represents unprincipled accommodation or foolishly applying rigid formulas.
Source: *Huainanzi*, Chapter "Explaining the Forest"
Meaning of the Idiom: Later, the Chinese idiom "削足适履" came to describe how forcing oneself to accommodate unreasonable things.