  An Old Horse Knows the Way 老马识途

  In the Spring and Autumn Period, Duke 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 howling. The troops 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 horse to be selected to lead the army. Finally, they found the way back home. 
  春秋时代，齐桓公出征攻打北方一个小国。去的时候是春天，遍地绿草茵茵。回来的时候是冬天，白雪茫茫，狂风怒吼，于是齐桓公的队伍迷失了方向。找不到回去的路，大家都很着急。这时，齐桓公的宰相管仲说："可以利用老马的经验。"于是齐桓公派人挑选了几匹老马在前面引路，果然走出了迷谷，找到了回去的道路。

  This idiom refers to the value of experience.
  "老马识途"这个成语用来比喻有经验的人，熟悉情况，办事效果好。