One time Duke Huan of the state of Qi inspected the stable and asked the officer who was in charge of the stable, "What is the most difficult thing to do in a stable?"

Before the officer had time to reply, prime minister Guan Zhong picked up the topic and answered, "I once kept horse and I know this well. Binding the fence is the most difficult thing to do in a stable. If you use bent wood first, then if the first one is bent, the other ones should also be bent ones. Even if there is straight one left, it still cannot be used. If you first use a straight wood, then all the other ones must be straight too. Even if there is not enough straight wood, the bent ones cannot be used instead."

齐桓公视察马棚，问负责养马的官吏：“马棚里什么事最难做？”

养马的官吏还没来得及回答，相国管仲接过话茬回答说：“我曾经养过马，对这个问题比较清楚。绑扎马棚的栅栏是最难做的活。如果先用弯曲的木头，第一根是弯的，后面的就必须用弯的；即使有直木头剩在那儿，也不可能用上。要是先用直木头，第一根是直的，后面的就全部要用直的，即使木头直的不够用，也不可能用弯曲的木头来补充。”