A crow perishing with thirst saw a pitcher1, and hoping to findwater, flew to it with delight. When he reached it, hediscovered to his grief that it contained so little water that hecould not possibly get at it. He tried everything he could thinkof to reach the water, but all his efforts were in vain. At lasthe collected as many stones as he could carry and dropped themone by one with his beak2 into the pitcher, until he brought thewater within his reach and thus saved his life. 
Necessity is the mother of invention. 