1It is an honour to be asked to introduce this excellent collection of studies of Cassius Dio and his Roman History, and all the more so since the editors have taken as their starting-point my doctoral thesis on Dio, published in 1964. Looking back, it is clear that I was very fortunate, first, in starting research under Sir Ronald Syme in 1958, the year in which he published his great work on Tacitus. It was thus possible to see Dio also as ‘a provincial at Rome’. Secondly, I benefitted from the guidance of a major historian of the Hellenistic period, Peter Fraser, whose knowledge of all parts of the Greek world, from Acarnania to Cyrene, Egypt or Bactria, was unsurpassed.

2All the same, I did not at that time appreciate what a major achievement Dio’s History was. First, in sheer scale. We can of course see this, up to a point, in the masterly edition by U.P. Boissevain, while noting his anguished protest at the end of the Preface to vol. III, published in 1900, over British conduct in the Boer War in South Africa. In the main surviving section of Dio’s text, from Books 37 to 57, each book occupies, in Boissevain’s edition, some 33 pp. So the complete original text of 80 books, if it were ever to be recovered, would take some 2640 pp. to print, and our knowledge of the narrative history of the Middle Republic, after the end of Livy’s text, would be transformed, as would the history of the Empire from Tiberius to Dio’s second consulate in CE 229.

3Nor did I see then that we could reasonably regard the Severan period as the high point of Imperial history. It is not just that this was, after Severus’ acquisition of Osrhoene and Mesopotamia, the moment of the greatest geographical expansion of the Empire. Perhaps few of our contemporaries, following with despair the unfolding of events in the Middle East, realise that Hatra had once, in the 230s, been occupied by Roman troops, and that Singara (Sinjar) had had, for a century and a half, the status of a Roman colonia. More significant still, this was the age of the greatest Roman jurists, whose works, dismembered for inclusion in Justinian’s Digest, represent one of the most important and distinctive products of Roman thought and literature. It was then too that a fusion of Greek and Roman culture was most fully achieved, a process symbolised by the Roman History, written in Greek, by Cassius Dio from Nicaea, and the vast display of juristic learning produced in Latin by his direct contemporary, Ulpian, from Tyre. As it happens these two were the only contemporaries known to us who referred to the universal grant of the Roman citizenship by Caracalla, entitled by moderns the Constitutio Antoniniana.

4It is of course a familiar paradox that our understanding of the narrative history of the age of Cicero and Augustus depends on works written in Greek in the Imperial period, by Plutarch, Appian and Dio. But it should be acknowledged that, as history, Dio’s writing is by far the most significant of the three – detailed, coherent and carefully structured, with impressive analyses of, for instance, the transition from republic to monarchy or the governmental structure of the Empire (in the light of much new evidence, perhaps the reflections on the Imperial system which Dio puts into the mouth of Maecenas in Book 52 would deserve further study). At the most basic level, it is on Dio’s narrative of the Later Republic and the reign of Augustus that all modern accounts depend.

5I have on occasion asked myself what Byzantine readers, living under a monarchy, can have made of Dio’s vivid narratives of late Republican conflicts (think for instance of his account of the consulship of Julius Caesar in 59 BC or of the tribunate of Clodius in 58 – and for that matter what would we make of Cicero’s letters from these years, if we did not have the framework provided by Dio?). But now we may be able to understand the Byzantine perspective, and the value of Dio for Byzantine readers, much better. For, first, we have the two excellent sections on the life and work of Xiphilinus in the eleventh century and (in much more detail) of Zonaras in the twelfth, which are to be found in Warren Treadgold’s masterly treatment of The Middle Byzantine Historians, published in 2013. This could be read in parallel with Antony Kaldellis’s survey of the (selective) Byzantine preservation of Greek historiography in the Journal of Hellenic Studies 2012. Furthermore, we can now read Kaldellis’ challenging book, The Byzantine Republic: people and power in New Rome, published by Harvard U.P. in 2015, which argues strongly that the Byzantine State itself was more open system than has been believed until now, and one in which popular reactions played a considerable part. If this thesis is accepted, we may be able to discern a further reason why Dio’s History was so valued in the Byzantine world. The meaning that it could have for a Byzantine scholar is brought out most clearly by Xiphilinus in his Epitome of Dio, when he reaches the constitutional settlement of 27 BC (trans. Kaldellis):

“I will now recount each event to the degree that it is necessary, especially from this point on, because our own lives and politeuma depend fully on what happened at that time, I say this now no longer as Dio of Prousa [sic], who lived under the emperors Severus and Alexander, but as Ioannes Xiphilinus, the nephew of Ioannes the patriarch, I who am composing this epitome of the many books under the emperor Michael Doukas”.

6That the Historia was indeed valued is shown beyond question by the rich and varied manuscript tradition (embracing full texts, extracts and epitomes) which was set out so carefully by Boissevain over a century ago. Even from the partial text which we have, there is still much to be explored and discussed. The Dioneia project is a most impressive contribution to that process.