Compare any two maps of the world and a host of differences will become apparent. Placenames vary across time and culture, but so too do the geophysical and biological features represented and the determination of a "centre" and a "top". In one map, for instance, a landmass labelled "North America" may be centre and top, in another it may be "Europa"; one may chart the flow of rivers, another human migration. Smaller differences are also apparent, from the colours used — for example, blue means water, pink means British Empire — to the fonts used in labels. World histories too come in a wide array of forms, varying in rhetorical structure, organizing principles and labels, foci and spatial and temporal breadth. Differences are most apparent when multiple works are produced on the same problem, period or event. To take just one example, in recent years the works of — among others — Andre Gunder Frank, Ken Pomeranz, R. Bin Wong and Angus Maddison have stimulated a lively debate on areas of growth in the eighteenth-century world economy and, more generally, "Eurocentrism" in the writing of world history.¹ The volume of works produced on this topic is now so large that there are surveys devoted to it.²