Abolish border controls. Let in large numbers of immigrants. Can this author be serious? Or realistic? That may be the immediate response to this book's evidence in favour of getting rid of the costly, often inhumane and only partially effective barriers which the United States has set up along its lengthy borders with Mexico, or with which Europe and Australia have surrounded themselves. But the whole apparatus of passports, visas and fenced borders is relatively new in history. It never used to be regarded as necessary. Nor were immigrants usually seen as threatening. The United States, Canada and the Latin American countries were built on migration, while Europe has over the past fifty years actively encouraged largescale immigration. Jonathan Moses puts the arguments in favour of free mobility across national borders, and counters those against. His conclusions are clear and profound: free international migration can lessen the huge material inequalities and human injustices that many associate with today's globalization.