Explanation: 【Source】 Ming Feng Meng, "Jingshitongyan Show gold Lingshi Meibi pay child": "with gold and closed the door, and two Cuxi go into the details. Is: wear out iron shoes in hunting, must come to not a waste of effort ! "【】 analogy to explain things that need with a great deal of effort could not find it inadvertently got. 【Example】 【】 story