Li Gang, styled Boji, was a Song Dynasty official from Shaowu (modern Fujian). A Jinshi scholar during Emperor Huizong's reign, he served as Vice Minister of the Imperial Secretariat and was briefly appointed Chancellor under Emperor Gaozong, only to be demoted after seventy days. Known for his unwavering loyalty and staunch opposition to peace talks with the Jin invaders, Li Gang famously declared during the siege of Kaifeng in 1126, "Our ancestors' lands must be defended to the death—not an inch shall be ceded to the enemy!"
When enemy troops besieged the city, Li Gang personally took to the battlefield to oversee the defense, boosting morale so greatly that soldiers and civilians rallied together in a single surge of effort and drove back the attackers. Yet the incompetent emperor heeded slander from the peace faction, leading to Li Gang's repeated demotions. A man who took the rise and fall of his nation as his own responsibility, Li Gang never cared about personal gain or loss—whether in office or in exile, he constantly submitted memorials advocating strategies to resist the Jin forces, and though none were ever adopted, he never grew discouraged. His awe-inspiring integrity was so formidable that even the enemy held him in deep respect; whenever a Song envoy arrived among the Jin, they would always ask whether Li Gang was well.
Li Gang once wrote a poem titled "Sick Ox," which, despite its title, uses personification to express the author's aspirations and emotions.
The poem has four lines: "Plowing a thousand acres fills a thousand barns, but when utterly exhausted, who pities you? Yet if all beings can be fed, I do not mind lying weak and sick in the setting sun."
The poem's essence: The ox toils for its master, plowing thousands of acres, filling his granaries—yet who pities the beast exhausted of all strength? As long as the common people have enough to eat, it gladly endures even the inability to rise from fatigue.
Later, the idiom "completely exhausted" came to describe extreme fatigue, with no strength left at all.
Source: Li Gang (Song Dynasty), *Sick Ox*
Meaning of the Idiom: Later, the Chinese idiom "精疲力尽" came to describe extreme fatigue, with no strength left at all.