The Great Delusion is about the unrealistic expectations we all have about what this tired and picked-over planet can provide us. It is about economic growth, the belief that a society can—even that it must—increase in wealth and population without end. I think that growth as we know it entered the American imagination in the 1840s—at the moment when an older faith in progress met the capacity to manufacture things on a large scale. Just watching steam engines made people think that energy and matter could be appropriated into this new system without end. Material progress became a popular expectation and, in time, a government policy. But the book is also a biography. I pin all of these ideas—and many more having to do with energy and resources—to an obscure German engineer named John Etzler. Why? Because Etzler took the most rational scientific ideas of his time and formulated them into a scheme to create infinite wealth with infinite energy for a world population that he hoped would top one trillion in his lifetime. The point is that if Etzler was crazy, so are we. Our presidential candidates might not use words like “infinite abundance,” but when they talk about prosperity without regard to planetary limits, when they promote growth as the cure for income inequality, they participate in the very same delusion.