Sketchy Notion of Perfection

My ten year old son came with me to work last week. Naturally in this environment he sat down, picked up a pencil and quickly started drawing. Almost immediately he asked for an eraser. "I don't have one", I told him. He looked around this design studio; paper, pencils, pens, markers, drawing equipment of all sorts all over it, sketches sprawled out over every surface, pictures on the walls, models in the corner, and he looked at me incredulously, "you don't have an eraser? How do you rub things out?".