Bezos decided to break away from Shaw to start a prototype, but he “concluded that a true everything store would be impractical—at least at the beginning.” He therefore analyzed twenty possible product categories for his new company, including clothes, software, music, and office supplies. According to the principles of mathematics, physics, and finance Bezos applied, books were the best choice. They were “pure commodities” in the sense that a book in one store was exactly the same as a book in another. They were easy to pack and hard to damage. And “there were three million books in print worldwide, far more than a Barnes & Noble or a Borders superstore could ever stock.” Thus an online bookstore would allow Bezos to promote “unlimited selection,” the most important insight that had attracted him and Shaw to the vision of Internet-empowered retailing.