The two most fundamental transformations of economic life in human history were the Neolithic food revolution and the industrial revolution. It is no surprise that the latter was unexpected by contemporaries, but it is intriguing and instructive that those who were best informed, such as, for example, Adam Smith and the other classical economists, were explicit that such a transformation was impossible. The paradox can be resolved, however, by considering the role of energy supply in the transformation which was taking place.