What is money, and how does it work? In this tour de force of political, cultural, and economic history, Felix Martin challenges nothing less than our conventional understanding of one of humankind's greatest inventions. Martin describes how the Western idea of money emerged in the ancient world, and was shaped over the centuries by tensions between sovereigns and the emerging middle classes. Money, he argues, has always been an intensely political instrument, and that it is our failure to remember this that led to the crisis in our financial system and the Great Recession. He concludes with practical solutions for making money serve us--and, in an introduction and epilogue new to this edition, a discussion of what Bitcoin and other cryptocurrencies mean for money's future. From John Locke to Montesquieu, from Sparta to the Soviet Union, Money is a far-ranging and magisterial work of history and economics, with profound implications for the world today.