Diodorus of Agyrium in Sicily-hence, "Diodorus Siculus"-was the author of the Bibliotheke, a "universal history" in forty books. It covers the story of the human race from Creation to the times of Diodorus in the late Roman Republic. Not counting the mythological section of the Bibliotheke (which treats the period before the Trojan War), Diodorus calculates (1.5.1) that he chronicled a period of 1138 years. To be sure, the work is the largest extant Greek history from ancient times and is the only extensive historical work, from either a Greek or a Roman writer, to have come down to us from the late Republic. Even the harshest critics of Diodorus-MacCauley referred to him as a "stupid, credulous, posing old ass"-must allow for the fact that significant portions of ancient history can only be reconstructed with the Bibliotheke as a guide. More recently (see below), Diodorus has been shown to have exercised considerable historical acumen and a measure of originality in the composition of Bibliotheke. St. Jerome's Chronology (155 ed. Helm) indicates that by 49 B.C. Diodorus was an established historian. The author of the Suda, erroneously it seems, places his floruit during and after Augustus' rule. Almost everything else about the life of Diodorus is culled from his writings. He indicates that his home town of Agyrium was at one time important-even the mythological hero Heracles is said to have stayed overnight-and that it enjoyed its peak of prosperity in the fourth century, when Timoleon settled 10,000 colonists there. Diodorus claims (Diod. 1.44.1) to have traveled to Egypt during the 180th Olympiad (60/59-57/6 B.C.), and to have begun his research there for the Bibliotheke. According to K. Sacks, Diodorus Siculus (Princeton 1990) 165, it is at least possible that Diodorus worked in some official capacity for Roman delegations while in Egypt. We can also surmise that Diodorus enjoyed a high station in Egypt, since he seems to have associated freely with the priests and embassies there. His work as a historian later took him to Rome, perhaps as early as 56 (Sacks 160), where by his own account (Diod. 1.4.3) he spent "a long time." Even before his arrival there, Diodorus had learned Latin from his many associations with Romans in Sicily (Diod. 1.4.4). It is doubtful that he ever acquired Roman citizenship, since we do not hear of a praenomen or nomen (Sacks 164). Besides the stays in Egypt and Rome, Diodorus does not appear to have traveled widely, and this may account for some of the lapses in his geographical knowledge (he writes erroneously [Diod. 2.3.2] that Nineveh is on the Euphrates). He does, nevertheless, complain (Diod. 1.4.1) about the many hardships he had to endure while doing his research and writing, and describes (Diod. 1.3.6) the thirty-year project as ponon polun (“immense work”). The Bibliothekewas published around 30 B.C., and its author may have lived into the next century. An epitaph from Agyrium, IG XIV 548, one of the only two extant inscriptions from the city, mentions "Diodorus son of Apollonius." Perhaps this was the tombstone of our historian (but see Sacks 161, n. 4). Of the forty original books of the Bibliotheke, 1-5 and 11-20 are wholly extant; the rest exist in part only. The work is a universal history, both in terms of the area covered and the time spanned. The first part treats the myths of Greeks and non-Greeks alike, from the beginning to the Trojan War; the second part, annalistically arranged, concludes with the death of Alexander (323 B.C.); and the third brings the history of the world down to Diodorus' time. In the extant books, we have the stories of the Egyptians, Assyrians, Ethiopians, and Greeks (1-5), and Greek history from 480-302 B.C. (11-20). (For the contents of the fragmentary books, see the outline in the introduction to the 12-volume Loeb Classical Library edition, pp. xv-xvi.) His motive for writing a universal history seems to have been related to the Stoic belief in a cosmopolis, whereby the history of all nations is of common interest to all. In his introduction (Diod. 1.1.1-5), Diodorus professes to be like an agent of Divine Providence and writes about the history of the human race as though it resided in a single polis. This view was given new meaning by the over-arching of Roman power in the first century B.C. For the most part, Diodorus looks kindly upon the Empire, and especially upon the Dictator (Sacks 160), but he can also direct his anger at the pleonexia of Roman rule (Diod. 31.26.2). Diodorus seems committed to the notion that there is a didactic purpose to history, and claims that through its study one can see the universal application of certain moral values (Sacks 82). According to Diodorus, history is replete with lessons that can instruct individuals as well as states about right and wrong conduct: we can learn, for example, from the rise of King Philip of Macedonia that his reverence towards Apollo's sanctuary at Delphi was the right course of action, while conversely we can see from the demise of the Phocians what happens to those who desecrate the shrine of Apollo. Although critics have conceded some merits to Diodorus as a historian, for example, his laudable adherence to a strict chronology (albeit in imitation of Apollodorus) or his immense industry, nevertheless much of the scholarship of the last century and a half has focused on the issue of his dependence on his sources. Until recently, the commonly held view had been that the Bibliothekewas a mere compilation of earlier sources (like Hecataeus, Ctesias, Ephorus, Theopompus, Timaeus, etc.) and that no one would read Diodorus if we had these (cf. OCD, 2nd ed. s.v.). With the recent publication of the book on Diodorus by K. Sacks, a more balanced view can now be taken regarding this issue of originality. Sacks argues effectively that Diodorus was more than a preserver of earlier traditions: indeed, he was "responsible for much non-narrative material and determined the overall shape and main themes of the history" (p. 5). In any case, even as a mere repository of earlier works, the Bibliothekeis of great importance, as it is often the sole or primary source of information regarding major periods of ancient history, such as the Pentekontaetia or the rise of Philip of Macedon. And we can surely agree with Pliny's assessment of Diodorus: "Apud Graecos desiit nugari Diodorus" (NH praef. 25).
For quick reference, the article in OCD (2nd ed.) by A. H. McDonald and the introduction to the Loeb Classical Library edition (vols. 1-12, 1933-67) by C. H. Oldfather et al. are helpful. G. Bowersock, Augustus and the Greek World (Oxford 1965), provides useful background information on the intellectual climate from about the time of Diodorus. K. Sacks, Diodorus Siculus and the First Century (Princeton 1990), is a model of investigative scholarship and will surely be the standard work on the subject for a long time. It has a full bibliography. Blaise Nagy