"People discovered new energy sources – coal, then petroleum – in the nineteenth century, and then invented all sorts of new technologies to make use of this freshly released energy. Transportation, manufacturing, agriculture, lighting, heating – all were revolutionized, and the results reached deep into the lives of everyone in the industrialized world. Everybody became utterly dependent on the new gadgets; on imported, chemically fertilized food; on chemically synthesized and fossil-fuel-delivered therapeutic drugs; on the very idea of perpetual growth (after all, it would always be possible to produce more energy to fuel more transportation and manufacturing – wouldn’t it?). Well, if the nineteenth and twentieth centuries were the upside of the growth curve, th[e twenty-first] century has been the downside – the cliff. It should have been perfectly obvious to everyone that the energy sources on which they were coming to rely were exhaustible. Somehow the thought never sank in very deep."