An old horse that could once cover a thousand li a day was now aged. Its owner thought, "It can no longer charge into battle, but surely it can still pull a cart?" So he hitched the horse to a heavily loaded salt cart and sent it up the Taihang Mountains.
The old horse arched its back, lowered its head, and struggled to climb, step by step, finally reaching a relatively flat spot halfway up the mountain, drenched in sweat and gasping for breath, so it stopped. The driver cracked his whip and shouted for the horse to continue. Forced onward, the horse barely managed a short distance before stopping again, its belly heaving violently and legs trembling with exhaustion. Impatient, the driver lashed it twice, and the horse, feeling a searing pain, strained to move forward, but the salt cart behind it remained as immovable as Mount Tai. Dizzy and seeing stars, the old horse just hung its head, tears glistening in its weary eyes, ignoring the shouts and blows.
Just then, Bole happened to pass by and saw that the horse collapsed from pulling the cart was actually an exceptional steed. He immediately jumped off his own carriage, rushed over, leaned against the shaft, and burst into loud sobs. Taking off his own robe, he draped it over the horse's back. Deeply moved, the horse knew it had found a true kindred spirit. It gently nuzzled Bole with its head, then raised its head and let out a long, mournful neigh, as if saying, "I am a thousand-li horse, but I am old now!"
Later, the idiom "A Salt Cart on a Steep Slope" came to describe talented people too old to shoulder heavy responsibilities.
Source: *Strategies of the Warring States*, Chapter "Strategies of Chu IV"
Meaning of the Idiom: Later, the Chinese idiom "峻阪盐车" came to describe how talented people too old to shoulder heavy responsibilities.