Aesop wrote:

A dog was crossing a plank bridge over a stream with a piece of meat in his mouth, when he happened to see his own reflection in the water.  He thought it was another dog with a piece of meat twice as big; so he let go of his own, and flew at the other dog to get the other piece.  But, of course, all that happened was that he got neither; for one was only a reflection, and the other was carried away by a current.

What do you think this fable means?