Theodor Mommsen is the only historian ever to have won the Nobel Prize for Literature. Radical politician as much as pedantic polymath, popularising journalist as much as retiring academic, his multi-volume History of Rome started to appear in the 1850s and was one of the inter- national publishing successes of the late-19th century. Running into 16 editions, and almost instantly translated from the original German into Italian, Russian, English, French, Polish, Hungarian and Spanish, it outstripped even such other contemporary classics as Frazer's The Golden Bough.
Yet it was never finished. Volumes One to Three appeared quickly within the space of a few years, covering Rome's history during the so-called "Republic" - a period of constitutional government under the Senate and elected magistrates - that Mommsen enthusiastically saw as a model for the new nation-states of Europe; Volume Five followed 30 years, later (a much drier history of the various provinces of the Roman empire). Volume Four, which was to cover Rome under the emperors, after the tyranny and assassination of Julius Caesar, never appeared. There was no doubt what Mommsen thought of this period; he repeatedly referred to it in his writing as a "deeply degenerate age" of "leaden tedium" destroyed by "inner putresence".
In 1980, however, a young German historian walked into a second-hand bookshop in Nuremberg, and came across a pile of old notebooks. These turned out to contain students' notes from Mommsen's courses on the history of the Roman empire in the 1880s - the closest thing, as their discoverer instantly realised, that we would ever get to the missing Volume Four. Edited into connected prose, they were published in Germany in 1992 to front-page headlines and they are now translated into English.
The serendipity of this whole story is astonishing; the chances that (even in well-educated Nuremberg) the books would have been spotted by someone who actually recognised what they were are almost too small to contemplate. …