How many books did Diodorus Siculus originally intend to write?

Abstract

Diodorus Siculus was notoriously inconsistent in his statements about the terminal date of his survey of history, theBibliotheca Historica. In the ‘table of contents’ (1.4.7) which he included in the general preface to the whole work, written apparently when he was preparing his manuscript for publication (probably about 30b.c.), he specifically names the year 60/59 (‘the first year of the 180th Olympiad, when Herodes was archon at Athens’) as the last year of his narrative. Elsewhere, however, he not only gives a figure for the period of history encompassed by his work which would bring it down to 46/5, but he also on several occasions expresses the intention of including within his narrative some account of Julius Caesar's activities in Gaul, which implies a terminal date later than c. 52 B.C. How can this discrepancy be explained? The most economical hypothesis would be that Diodorus set out at first to compose a work that should go down to 46/5, but at some later stage in the composition changed his mind, and set back his terminus to 60/59. His originally intended terminus was most likely the triple triumph of Julius Caesar, whom Diodorus clearly admired beyond all other contemporary leaders. The decision in favour of an earlier terminus will have been due either to simple fatigue or to disillusionment with the course followed by Caesar's heir after 44b.c.and anxiety about the dangers of dealing with events of a too recent and controversial past.