Methodological practice is at the heart of divisions between schools of macroeconomic thought. Jesper Jespersen's book explains why and precisely how, and gives the reader the insight to choose between rival approaches. His own inspiration comes from Critical Realism and Popper's Three World analysis, with Keynes as the main exponent of a realist approach. The starting point of realist theory is a view of how the world is, rather than axioms, and the test is whether the theory can make, as Jespersen puts it, the "round trip back to reality", to give practical guidance to policy. This is only the focal point of a rich and attractive canvas.