Are You The Eraser Or The Pencil?

Pencil: I'm sorry.... 

Eraser: For what? You didn't do anything wrong. 

Pencil: I'm sorry cos you get hurt bcos of me. Whenever I made a mistake, you're always there to erase it. But as you make my mistakes vanish, you lose a part of yourself. You get smaller and smaller each time. 

Eraser: That's true. But I don't really mind. You see, I was made to do this. I was made to help you whenever you do something wrong. Even though one day, I know I'll be gone and you'll replace me with a new one, I'm actually happy with my job. So please, stop worrying. I hate seeing you sad. :)