This book examines the origins of the IS-LM model, one of the most significant innovations in the history of economic thought. It shows that the complete IS-LM model, including the equations and diagram, was produced by a group of economists who contributed their respective mathematical models of Keynes’s General Theory, including Champernowne, Reddaway, Harrod, and Meade, not to mention Hicks. Furthermore, the book discusses the implications of newly discovered archival material, including a previously overlooked document showing that John Maynard Keynes himself was the first to present...