“Can I ask about that pencil in your hair?” Roth tried again. “Of course,” she said. “It’s a number-two pencil. ‘Two’ signifies the lead hardness, although pencils don’t actually contain lead. They contain graphite, which is a carbon allotrope.” “No, I meant why a—” “A pencil instead of a pen? Because unlike ink, graphite is erasable. People make mistakes, Mr. Roth. A pencil allows one to clear the mistake and move on. Scientists expect mistakes, and because of it, we embrace failure.”
