The process which has resulted in this book began many decades ago when, as an undergraduate student, I found myself asking the question, ‘What did the Romans think they were doing when they created the Roman Empire?’ For many years this question lurked in the background of my thoughts as I worked on Roman history more generally and on Roman Spain in particular, not least because it was not clear to me how such a question might be answered. What follows is, I hope, if not an answer, at least a contribution towards one. It emerged not least from a remark made in passing by Fergus Millar, that to understand what imperium meant it would be necessary to read the whole of Latin literature. I have not quite done that, but the development of accessible digital texts has made possible the next best thing, the scanning of large quantities of texts to discover the passages in which both imperium and its stablemate, provincia, appeared. I should give due recognition to the Packard Humanities Institute and the Thesaurus Linguae Graecae project of the University of California, without whose excellent productions the work of this book would have taken several lifetimes. I also mention, honoris causa, two pieces of software which have been indispensable: the search program Musaios, developed since 1992 by Darl J. Dumont and Randall M. Smith; and the database program, Idealist. These two enabled me to assemble a database of several thousands of passages from ancient authors, which were further analysed with the help of an Excel spreadsheet.