The Latin language has been the one constant in the cultural history of the West for more than two millennia. It has been the foundation of our education, and has defined the way in which we express our thoughts, our faith, and our knowledge of how the world functions. Indeed, the language has proved far more enduring than its empire in Rome, its use echoing on in the law codes of half the world, in the terminologies of modern science, and until forty years ago, in the liturgy of the Catholic Church. It is the unseen substance that makes us members of the Western world. In his erudite and entertaining "biography," Nicholas Ostler shows how and why (against the odds, through conquest from within and without) Latin survived and thrived even as its creators and other languages failed. Originally the dialect of Rome and its surrounds, Latin supplanted its neighbors to become, by conquest and settlement, the language of all Italy, and then of Western Europe and North Africa. Its cultural creep toward Greek in the East led it to copy and then ally with it in an unprecedented, but invincible combination: Greek theory and Roman practice, delivered through Latin, became the foundation of Western civilization. Christianity, a latecomer, then joined the alliance, and became vital to Latin's survival when the empire collapsed. Spoken Latin re-emerged as a host of new languages, from Portuguese and Spanish in the west to Romanian in the east. But a knowledge of Latin lived on as the common code of European thought, and inspired the founders of Europe's New World in the Americas. E pluribus unum. Illuminating the extravaganza of its past, Nicholas Ostler makes clear that, in a thousand echoes, Latin lives on, ad infinitum.