In February , as I was writing this paper, the Financial Times reported at length on an upcoming British Museum exhibition on 16 th -century Persia: “the third in a series on great world empires,” following a “hugely popular show” featuring the terra cotta soldiers of the great Ch’in emperor, a second exhibition on Hadrian, and to be followed in turn by a show on the Aztec emperor Moctezuma II. The director, Neil MacGregor’s “overall concept for the series is to study the ‘instruments of cohesion’ that held those empires together and ask what the consequences of their dominion have been in the long term.” 1 And so by means of their artifacts, suitably displayed, empires past radiate their light downward to the present, like stars after extinction, allegedly educating us all, as Director MacGregor intends, in the interconnections of our species. Is it “interconnectedness,” as MacGregor believes, that makes empire so compelling a theme? Perhaps. A good exhibit does startle or delight us by revealing connections between remote societies and ultimately our own—whether of art, or beliefs, or commodities, alphabets and calendars, or germs and pathogens. After all, connections are the basis of one major contemporary approach to international history—that is they are the privileged subject of the contemporary effort to write “entangled histories” or what the French call histoires croisees, and the history of what many colleagues now like to call “cultural transfer.” And just as economists have developed the theory of the firm, as a way of minimiz ing the so-called transaction costs of contracts among buyers and sellers, Empires, in a sense, have been an institutional device for internalizing such cultural transfer. An empire provides a political structure for extending cultural transfer through time and space. Historians divide, as did policy makers, on the nature of that structure. For some of us it is a harsh one, built on power and domination; for others it has softer outlines and processes that we describe in terms of negotiation. Every subaltern people has agency; hence every transaction is negotiated—a flight of dubious logic, it seems to me. And for many, empire has the sentimental redolence of a wonderful and idealistic project. As a Swedish journalist explains what he termed the longest-term geopolitical project in world history, “The empire is gone, but the sun never