"A man goes out on the beach and sees that it's covered with starfish that have washed up in the tide. A little boy is walking along, picking them up and throwing them back in the water.
'What are you doing, son?' the man asks. 'You see how many starfish there are? You'll never make a difference.'
And the boy pauses thoughtfully, picks up another starfish, and throws it back into the ocean. 'It sure made a difference to that one,' he said."
(mentioned in Now I'll Tell You Everything by Phyllis Reynolds Naylor, story adapted from the essay "The Star Thrower" by Loren Eiseley)