In his 1887 novel Looking Backward, Edward Bellamy introduced the idea of credit cards. Thirty years later, hotels and gas-station chains began issuing them to customers. The modern-day slab of plastic came about in the 1950s with the introduction of the Diners Club card and, later on, Carte Blanche and American Express. In the near future, plastic will likely be replaced by something even less substantive cell-phone currency, a form of electronic money with no physical properties at all.