The Crow and the Pitcher

A crow perishing with thirst saw a pitcher and flew to it with delight, hoping to find water. When he reached it, he discovered to his grief that it contained so little water that he could not possibly reach it. He tried everything he could think of to reach the water, but all his efforts were in vain. At last, he collected as many stones as he could carry and dropped them one by one with his beak into the pitcher, until the water rose within his reach and he thus saved his life.

Necessity is the mother of invention.