In ancient times， there was a prime minister named Shang Yang in the State of Qin. He was held in high regard by the King.

In the year 359 BC， he prepared for a political reform to promote the economic development. But he was afraid that the people would not believe local authorities.

He thought an idea. One day， he had a 10-meter long pole erected at the south gate outside the capital. Then he told the crowd whoever took the pole to the north gate would be awarded 10 ounces of silver. Everyone was astonished， but nobody dared to have a try.

After seeing that， Shang Yang raised his voice and said：“Anyone who carries the pole to the north gate will get 50 ounces of silver.” A brave man did it and was be given 50 ounces of silver. Others felt very regretful.

In this way， Shang Yang achieved his aim successfully. Soon the state of Qin became the strongest country.

Later， people use it to praise the man who keeps his promise.