A young man was picking up objects off the beach and tossing them out into the sea. A second man approached him, and saw that the objects were starfish.
"Why in the world are you throwing starfish into the water?"
"If the starfish are still on the beach when the tide goes out and the sun rises high in the sky, they will die," replied the young man.
"That's ridiculous. There are thousands of miles of beach and millions of starfish. You can't really believe that what you're doing could possibly make a difference!"
The young man picked up another starfish, paused thoughtfully, and remarked as he tossed it out into the waves, "It makes a difference to this one."
from The Star Thrower
by Loren Eiseley