An old man walked the beach at dawn, when he noticed a young girl ahead of him picking up starfish and flinging them into the sea. After watching the hopeless situation, the man decided to catch up so he could talk to the ambitious youth. "Why are you doing this?" he asked the girl. The answer was that the stranded starfish would die if left in the morning sun.
"Sweetheart," the old man began, "don't you know that there are thousands of starfish on this beach? And don't you know that this beach goes on for miles and miles? There is no way in the world you can save all those starfish! For all your efforts, it doesn't make any real difference."
The young girl looked thoughtfully at the starfish in her hand and then threw it to the safety of the waves, saying, "It makes a difference to this one".
--Adapted from "The Star Thrower," by Loren Eiseley