In the Spring and Autumn Period, Duke Huan of Qi led his army to attack a small northern state. They set out in spring when the land was covered in green grass. However, upon their return in winter, the landscape was transformed—blanketed in snow and swept by howling winds. The troops lost their way.
As everyone grew anxious, Guan Zhong, the Duke's chief minister, offered a suggestion: "An old horse may know the way." Following this advice, the Duke ordered several old horses to be selected to lead the army. Guided by the horses, they finally found their way home.
This idiom highlights the value of experience.