Book excerpt: Is the theory of money that underlies most modern macroeconomics well-grounded? What determines the value of a currency, and how is the state's power over its currency related to its ability to stabilize prices and employment? Charles Goodhart's classic paper 'The Two Concepts of Money: Implications for the Analysis of Optimal Currency Areas' which first raised these questions is reprinted here, and the distinguished authors expand its line of argument and comment on its central themes. The issues discussed are of fundamental importance in contemporary monetary theory and policy. The State, the Market and the Euro presents two sharply contrasting theories of money - Chartalist and Metallist - and the resulting equally sharply contrasting approaches to macroeconomic policy. Academic monetary, financial and political economists will find this book of great interest as will policymakers, financial analysts and journalists.