Everyone has an interest in time, but historians are interested in it professionally. they have been remarkably fecund in devising ways to carve up and label the mysterious workings of time. They have named it after rulers or other leaders (what the great French historian of the Annales school Marc Bloch referred to tartly as “stumbling from reign to reign” [177]), so that students encounter periods called the Napoleonic, Jacksonian, Victorian, Meiji, and Wilhelmine, to give just a few examples from the nineteenth century I know best. Then there are the centuries, the building blocks of so many survey courses and textbooks that one can only wonder at the powerful hold of the decimal system on the historical imagination. Not least, of course, we find history divided into conceptual units. These may be variations on ancient and modern; they may be periods defined by a body of ideas and practices (Renaissance, Enlightenment) or by overarching political and social developments (the revolutionary era, the age of empire). Once we enter the terrain of conceptually defined eras, titles given by historians are limited only by the number of abstract nouns that can be employed after the phrase “age of,” starting with “anxiety” and continuing through the alphabet.