When the Roman historian Tacitus wrote the Germania, a none-too-flattering little book about the ancient Germans, he could not have foreseen that centuries later the Nazis would extol it as “a bible” and vow to resurrect Germany on its grounds. But the Germania inspired—and polarized—readers long before the rise of the Third Reich. In this captivating history, Christopher B. Krebs, a professor of classics at Stanford University, traces the wide-ranging influence of the Germania, revealing how an ancient text rose to take its place among the most dangerous books in the world.