Long long ago, there was a clam（蛤） raiser who wanted to make the biggest pearl in the world. He went to seaside to select sand grains. He asked the sand grains whether they wanted to turn into pearls , but in vain. Clam raiser despaired. Finally one agreed. 

Any other sand grains all laughed at him, because he would live in the clam, and stay away from relatives and friends, and could not see sunshine, rain and dew（露水）, bright moon, pleasant breeze, and could only be associated with dark, damp, cold and lonely. That would not be worthwhile. 

Some years ago, the sand grain had grown into a priceless pearl. The sand grains laughed at him were still a pile of sand while some had been into soil.

If we say there are something that could catch the stone and turn it into gold, that is hardship and pain. Endure pain and insist, when you go through the long tunnel of dark and misery, the ordinary you, just as the sand grain, have grown into a peal.