The little puppy

One day there was a little puppy dog laying beside one of the rails on a railroad track.

He fell asleep,and while he was sleeping his tail ended up on the rail, and by that time a train came along and cut off his tail,he look around to see what happen and the train cut off his head------

Do you know what the moral of the story is?

Dont lose your head over a little piece of tail !!