A story of this idiom goes like this. Once upon a time, there were two mountains Taihang and Wangwu covering a territory of seven hundred square miles, with a ten thousand cubits height. They were formerly situated in the south of Jizhou and north of Heyang.
Old Man Yu Gong of the North Mountain was about ninety years old and he lived in a house facing the mountains. He did not like the mountains blocking his way and making him go up and down or around the mountains when he left home. One day, he asked his families to come together and said to them, “You and I shall set to work with all our strength and level the mountains so that we may have a path leading straight outside and reaching clear to the northern bank of the Han River. What do you say?” The family agreed, but his wife was worried, “With your strength, you can’t even do anything with a little hill. How can you move the two great mountains away? Besides, where are you going to put away all the rocks and soil?” The Old Man said, “We can throw them into the end of the Bohai Sea and the north of Yintu (Siberia).”
He then led three of his children and grandchildren, who could carry loads, chip the rocks and shovel the soil, and carried them in baskets to the end of the Bohai Sea. An orphan boy of the neighbor’s widow, who had just shed his milk teeth, jumped along and came to help them and returned home once a season. The Wise Man of nearby laughed at the Old Man and tried to stop him, saying, “What a fool you are! With all the strength and years left for you, you can’t even scratch the surface of this mountain. What can you do about the rocks and soil?” Old Man YU Gong drew a deep sigh and said, “Your mind is so blocked up that you cannot think straight. I cannot achieve my will definitely, but when I die, there will be my children to carry on the work, and the children will have grandchildren, and the grandchildren will again have children. So my children and grandchildren are endless, while the mountains cannot grow bigger in size. Why shouldn’t they be leveled some day?” The Wise Man could not make any reply.
Now the Mountain God heard about, the Old Man was worried that the leveling of the mountains would not cease, and then went to speak to God. God was touched by the Old Man’s sincerity of heart and ordered the two of his sons to carry the two mountains and placed one in Shuodong and one in Yongna. From then on, the south of Jizhou and north of the Han River became level ground, and the spirit of the Old Man Yu Gong has been passing down.