Addressing the Conservative Party conference in October, 2016, British Prime Minister Theresa May said: "If you believe you're a citizen of the world, you're a citizen of nowhere. You don't understand what the very word citizenship means." But what did she mean, by making this distinction? Today, we see nationalism on the rise from the United States to Russia, from China to India, and among most of the European Union member states. Stemming from the Engelsberg Seminar of 2017, the essays in this volume explore what it has meant to belong to nations and empires - from classical times to the most recent explosions of populism - and what it now means to belong to a particular state in a global economy.