The Dog and The Shadow

A Dog, crossing a bridge over a stream with a piece of flesh in his mouth, saw his own shadow in the water, and took it for another Dog, with a piece of meat double his own in size. He therefore let go his own, and fiercely attacked the other Dog, to get his larger piece from him. He thus lost both—that which he grasped at in the water, because it was a shadow and his own, because the stream swept it away.

It is not wise to be too greedy.