Part I. Theories and Problems: 1. Modelling the medieval economy: the equation of exchange2. Money and the money economy -- 3. Coinage and the bullion supply -- Part II. The Coinage and the Economy, 873-1489 A. A Monetised Economy: 4. The coinage from the late tenth century to 1158 -- 5. A monetised economy, 973-1158? -- B. The Emergence of a Money Economy, 1158-1351 -- 6. The coinage 1158-1351 -- 7. The making of a money economy, 1158-1351 -- C: The Money Economy Challenged, 1351-1489: 8. The coinage 1351-1489 -- 9. Testing the money economy, 1351-1489 -- 10. Conclusions.