Between the States of Jin and Guo lay the State of Yu.
Once, the State of Jin planned to invade Guo but needed permission to pass through Yu. The King of Jin worried Yu would refuse.
Xun Xi, a high official of Jin, proposed a scheme: "Offer the round jade and the fine steed as gifts to the King of Yu. He is sure to grant permission."
The King of Jin hesitated: "The jade from Chuiji is my ancestral treasure; the steed from Qudi is my favorite. What if he accepts the gifts but denies us passage?"
Xun Xi replied: "Unlikely. If he refuses passage, he will not dare accept the gifts. If he accepts and grants permission, it will be like moving the jade from an inner storehouse to an outer one, and the horse from an inner stable to an outer one. Why worry?"
As predicted, the King of Yu, coveting the treasures, was ready to agree.
His official, Gong Ziqi, urgently dissuaded him: "You must not consent! Guo is our neighbor. Our relationship is like that of lips and teeth. If the lips are gone, the teeth will be cold. If we let Jin invade Guo, once Guo falls, can Yu remain safe? Absolutely not!"
The King of Yu ignored this advice and consented.
Soon, Xun Xi led his forces and conquered Guo. Three years later, Jin conquered Yu as well. Xun Xi returned in triumph, carrying the jade and leading the horse, and returned them to the King of Jin.
The King, immensely pleased, smiled and said: "The jade remains the same; only the steed has aged a bit."