It’s a terrific story of Paul Romer and other economists trying to incorporate knowledge, expertise, and innovation into the classical economics model. The book includes substantial essays on the history of economic thought, from Adam Smith and Malthus, through John Meynard Keynes and Milton Friedman. One of the main points of “growth economics" is that technological progress drives growth, and to get more of it we need to facilitate the use of new knowledge and protect and incentivize invention (through well-enforced patent laws, better education systems, etc). But knowledge and expertise give us increasing returns to scale, as opposed to the diminishing returns to scale that drive classical economics.