A vacationer strolling along a starfish-strewn beach spies a person in the distance whom he believes is dancing. He is so intrigued he investigates further.
As he approaches the dancer, he realizes it is a young man and he is not really dancing, but is, in fact, picking up individual starfish, tens of thousands of which have been stranded by low tide, and throwing them, one by one, into the ocean.
The vacationer asks the man why he is undertaking such a monumental task and the man replies that the stranded starfish will die if he doesn't get them to water. The vacationer then scoffs and informs the man that there are miles and miles of beach and tens of thousands of starfish and he can't possibly believe that what he is doing will make a difference.
The young man pauses and gives thought to the vacationer's comments. Then he picks up a starfish from the beach, throws it back into the ocean, and tells the vacationer, "It made a difference to that one."