An old man walks along a beach and sees a young boy throwing something into water.
As he approaches, he sees hundreds of starfish lining the beach washed in from the tide.
The young boy is rushing around, throwing the starfish back into the water one by one.
The old man asks why he bothers, it's pointless. There are too many starfish to help them all.
As he flings a starfish deep into the water, the young boy replies:
It mattered to that one.