It was when President Kim Il Sung gave a field guidance to North Hamgyong Province.

Acquainting himself with situation of a county, the President came to know that officials in the county had trouble with stones in its fields.

Being told in detail about the problem by an official, the President asked him if they had ever thought to use the stones. The official could not give the President an answer as he had never thought of it.

The President said that it was necessary for the county to build terraced fields because it had many slopes. He said that other counties should carry stones from riversides or quarries to build terraced fields but the county could make immediate use of the stones in their fields.

The President said that building terraced fields had no bad points but many good ones such as saving labour in picking stones out of the fields, readjusting and improving land and protecting earth from landslide caused by rain.

It was a brilliant idea that enabled them to make effective use of the stones that had been regarded as useless.