Starfish

Many starfish washed up on shore.

A saintly man started picking them up and throwing them back into the ocean.

Someone saw what he was doing and told him that it was pointless, that there were too many to save, that it wouldn't make a difference.

Throwing another starfish into the sea, the saintly man responded, "It makes a difference to this one".

Source: http://www.vidyavikas.org/