I like the piece of paper example. Take a new sheet of paper, screw it up, flatten it back out. It is still a piece of paper, for all intents and purposes it will do everything a piece of paper should, but no matter what you try, you can never totally remove the marks made by screwing it up.
I love this quote, I always mean to remember it for appropriate moments but forget!
Due to increased spam comments I am now having to moderate the comments I receive. I will do my best to get them approved quickly so please, carry on commenting as every time you comment a kitten smiles.