TWENTY years ago, Thomas Sowell was one of the first scholars to document and analyze how immigrant blacks outperformed their U.S.-born counterparts. It is no surprise, then, that his latest book, Migrations and Cultures: A World View,† identifies enormous economic benefits flowing to migrants, to the homelands receiving their remittances, and to the societies hosting them. Sowell writes: “The history of immigration in all its various forms is an important part of the history of the advancement of the human race.”