To the dismay of many commentators - who had hoped the world was evolving into a more tolerant and multicultural community of nations united under the umbrellas of supranational movements like the European Union - the nationalism that was such a potent force in the history of the 20th-century has made a comeback in recent years. Now, more than ever, it seems important to understand what it is, how it works, and why it is so attractive to so many...