In the Spring and Autumn Period, Duke¹ Huan of Qi led an army to attack a small state in the north. They went in spring when green grass covered the ground. But when they came back it was winter. Everywhere was white with snow and the wind was howbing. The troops² lost their way. While everybody was worrying, Guan Zhong, the Duke's chief minister, suggested:"An old horse may know the way." So the duke ordered several old horses to be selected to lead the army. Finally, they found the way back home.

This idiom refers to the value of experience.

春秋时，齐桓公与大臣等仲、隰朋进攻孤竹国，回来时迷了路。管促说：老马能识途。于是让老马在前面走，大家跟着，果然找到了归路。见《韩非子·说林上》。后以"老马识途"等喻富有经验或富有经验的人。汪赵执信《为求书者所苦戏题长句》："诸君且休共和谈，老马识途犹尚堪。"