I am grateful to my editor Alex Wright for suggesting that I have a go at something that I would never have thought possible in the space of 90,000 words. I have enjoyed the challenge; I leave it to my readers to judge the success of my sketch of a vast topic. I am also grateful to David Rijser for inviting me to deliver the 2012 Amsterdam Vergil Lectures, based on the materials in this book, and to the stimulating audiences at those lectures.