I first began working on contact between Latin and other languages in an organised way when I had the good fortune to be Visiting Senior Research Fellow at St John's College, Oxford, in 1994–5. The project was given impetus by the invitation to deliver the J. H. Gray Lectures in the Faculty of Classics, University of Cambridge, in May 1999. The title of the lectures was the same as that of the present book. The subject turned out to have such ramifications, and the material relevant to it to be so scattered, that I might never have finished the book had I not had the even greater good fortune to be elected to a Senior Research Fellowship at All Souls College, Oxford, in 1997.

An account of the full range of bilingualism in the ancient world across the whole of the Mediterranean and Middle Eastern areas and at all recorded periods would be virtually unmanageable, unless a team of collaborators was assembled. I have restricted myself to the Roman period, from the early Republic to the late Empire (approximately the fourth century). I have not adopted a fixed cut-off point, but on the whole have avoided entering into the period of the barbarian invasions in the west. In the western Empire Latin came into conflict with a number of vernacular languages and eventually effected their death.