Edward Gibbon’s The History of the Decline and Fall of the Roman Empire (published in six volumes between 1776 and 1788) must rank among the best known of unread or partly read books. At over 3,000 pages it is written in the sometimes convoluted style of the eighteenth century and lingers over details which mean little now to most readers, not least disputes over the nature of the Holy Trinity. Yet this Everest of a book asks to be scaled and in the end retirement offered me leisure and the necessary oxygen to make the attempt.