[伊索寓言] 乌鸦喝水

The Crow and the Pitcher

A crow, on the verge of dying with thirst, spied a pitcher(水罐) in the distance and flew to it with joy...At last, seeing some small pebbles nearby, he gathered them and dropped them into the pitcher one by one.  By this means the water gradually rose to the brim(边缘), and he could quench(解渴) his thirst with ease.

Necessity is the mother of invention.