Along the coast of the vast Atlantic ocean there lived an old man. Each day when the tide went out he would make his way along the beach for miles. Another man who lived not far away would occasionally watch as he vanished into the distance and later notice that he had returned. The neighbor also noticed that, as he walked, the old man would often stoop down to lift something from the sand and then toss it away into the water.
One day, when the old man went down to the beach this neighbor followed to satisfy his curiosity and, sure enough, as he watched, the old man bent down and gently lifted something from the sand and threw it into the ocean. By the time the old man made his next stop the neighbor had come near enough to see that he was picking up a starfish which had been stranded by the retreating tide and would, of course, die of dehydration before the tide returned. As the old man turned to return to the ocean the neighbor called out with a degree of mockery in his voice, "Hey, old timer! What are you doing? This beach goes on for hundreds of miles, and thousands of starfish get washed up every day! Surely you don't think that throwing a few back is going to matter."
The old man listened and paused for a moment, then held the starfish in his hand out toward his neighbor. "It matters to this on."