Since Diodorus was a compiler rather than much of an original writer, it would be good to know which earlier historians were his sources for Books 16–20. In these books Diodorus was writing about events that took place around 250 years earlier than his lifetime. Under these circumstances, a historian is only as good as his sources—or as his discriminating use of those sources.
The following historians are the most likely sources followed by Diodorus in Books 16–20. I should stress that these are mostly scholarly guesses, since in our books Diodorus rarely names his sources, and at the same time we hardly ever have a fragment of the original sources that corresponds to Diodorus’ text and so can act as a control. I should also stress that there may be a number of lesser sources that we simply cannot identify. What follows should be regarded as a list of Diodorus’ main sources for Books 16–20, with the work of several others lurking untraceably below the surface.
Furthermore, we cannot always be sure whether Diodorus read every one of these historians himself, or whether in some cases their views came to him with another of his predecessors as intermediary. So he may not have read Ptolemy’s own account of Alexander’s eastern expedition, rather than Cleitarchus’ or Diyllus’ paraphrase of Ptolemy. This less thorough approach was typical of the Greek historians. As for Diodorus’ chronographic indicators—Olympiads, Athenian Archons, and Roman consuls—it is likely that he found all of these together in a single chronographic source, based ultimately on the work of Apollodorus of Athens (see 1.5.1), and that this source was a little-known writer called Castor of Rhodes, an older contemporary of Diodorus. Castor or a similar writer is probably also the source of a lot of Diodorus’ more incidental information: notices about the reigns of monarchs, the beginnings and endings of wars, and the foundation of cities.
agatharchides of cnidus (second century). Very little survives of Agatharchides’ historical work (as distinct from his account of an expedition to explore the Red Sea, of which more has survived), but he wrote a universal history covering both European and Asian affairs, with a strong geographical and ethnographical bent that would have attracted Diodorus. We know that Diodorus consulted him for Book 3 (see 3.11.2), and he very likely lies behind some stretches of other books as well, including Books 16–20.
anaximenes of lampsacus (fourth century) wrote extensively on Greek and Macedonian history. His mention at 15.89.3 makes it likely that he was one of Diodorus’ sources. He started his histories in mythological time, but he was not a universal historian in geographical terms; he was interested only in Greek history.
athanis (or athanas) of syracuse (fourth century), an almost unknown historian to us, was the continuator of the Sicilian history of Philistus (below). His mention at 15.94.4 suggests that he was consulted by Diodorus for Sicilian history.
callisthenes of olynthus (died 327). The nephew of the philosopher Aristotle, Callisthenes accompanied Alexander the Great on his expedition, until he was executed for treason. He wrote not just about Alexander (whom he greatly admired—until they fell out), but also a monograph on the Third Sacred War and a ten-book History of the Greeks down to 356 bce. Diodorus’ direct use of him was probably largely limited to the Sacred War (16.23–40, 16.56–64).
cleitarchus of alexandria (probably mid-third century). The so-called ‘vulgate’ tradition on Alexander the Great’s eastern expedition, consisting of Diodorus, Curtius, the Metz Epitome, and Justin, is held to have largely followed Cleitarchus.1 His twelve-book history was extremely popular, and was probably largely based on information acquired by autopsy and interview, leavened by Cleitarchus’ love of a good story. He did not personally accompany Alexander on his eastern expedition, but he drew on several historians who did.2 Very few fragments remain, but he was very likely Diodorus’ major source for the eastern expedition in Book 17, and therefore the nature of his work can be glimpsed through Diodorus’ reworking.
demodamas of miletus (third/second century). Demodamas is little more than a name to us, but he was a close associate of Seleucus, and some of the pro-Seleucid material of Book 19 may derive ultimately from him.
demophilus of cyme (later fourth century). Very little is known about this historian, the son of a more famous father, Ephorus. Diodorus tells us (16.14.3) that he completed his father’s history of Greece by writing or finishing the final, thirtieth book on the Third Sacred War, so it seems likely that Diodorus consulted him for this war.
demosthenes of athens (384–322). Some of Demosthenes’ work clearly lies behind the account of the weeks before the battle of Chaeronea (17.84–5), but this was probably already paraphrased in one of Diodorus’ main sources, perhaps Diyllus.
dinon of colophon (early fourth century). Dinon was the father of Cleitarchus, and wrote, apparently in a romantic vein, a three-part account of Persian history. His work may underlie some of Diodorus’ history of the Persians, especially as filtered through Cleitarchus. Ctesias of Cnidus and Heracleides of Cyme also wrote Persica in the fourth century, but Diodorus, or rather Cleitarchus, does not seem to have made use of them.
diyllus of athens (early third century). Diyllus wrote a universal history (including the western Greeks) starting with the Third Sacred War in 357 and ending with the death of Cassander in 297 (16.14.5)—that is, he deliberately started where Ephorus’ history ended (16.76.6). He may have been Diodorus’ main source for Philip’s and Alexander’s dealings with the Greeks, and an additional source for Sicilian history as well.
duris of samos (c.340–c.260). Duris was the tyrant of Samos (succeeding to his father’s position), but also found time to write a history of Macedon in about twenty-three books, a favourable biography of Agathocles of Syracuse (Duris may have been born in exile on Sicily), and a history of the island Samos. He has a reputation for having focused on sensational events, but that is probably an accidental result of his fragments having been preserved by authors who were attracted to sensationalism. It is unclear whether Diodorus used him directly, but his work may lie behind some of the Macedonian history that Diodorus recounts, the account of Alexander’s dealings with the Greeks in Book 17, and the account of Agathocles’ career in Books 19 and 20. He was a moralizing historian, emphasizing especially the deleterious effects of luxury and all forms of immoderation.
ephorus of cyme (c.400–330). Ephorus was Diodorus’ main source for much of The Library, for all of early Greek history until early in Book 16. Polybius calls him the first universal historian (Histories 5.33.1), though Diodorus criticizes him for having omitted the mythological period (4.1.2–3; see also 1.3.2–3). He started with the return of the Heraclidae (supposedly the first properly historical event) and at the time of his death had brought his history down to 357, with drafts of some future sections completed as well, down to 340. His son Demophilus (see above) completed the work by covering the Third Sacred War, which Ephorus had not yet written up. Despite being a universal historian, Ephorus did not make use of chronographic indicators such as Athenian Archons or Roman consuls, but divided time up by generations, and structured his work by alleged synchronicities between events of one part of the world and another. He had access to sound primary sources and approached them with a good, critical eye. He was the first to divide his own work into books (rather than leaving that to later editors) and to write a separate preface for each book, a practice followed by Diodorus. Ephorus’ presence is slight in Books 16–20, except for some of the material on Philip II’s early life and career, the material on Dion of Syracuse, and perhaps some Persian history.
hieronymus of cardia (354–250). Hieronymus first served Eumenes (who was a fellow citizen and probably a relative), and then, after Eumenes’ death, the Antigonids: Antigonus Monophthalmus (for whom, inter alia, he supervised the extraction of asphalt from the Dead Sea), Demetrius Poliorcetes (for whom, inter alia, he governed the Greek city of Thebes), and Antigonus Gonatas, the first king of a stable Macedon. The unique and often eyewitness perspective he gained thereby makes the loss of his History of the Successors particularly painful. His history started with the death of Alexander the Great in 323 and went up to the death of Pyrrhus in 272. Diodorus relied primarily on him for his account of the Successors in Books 18–20, and the quality of that account is generally held to be due to the superior quality of Hieronymus’ work. He seems to have been a sound and entertaining historian, a good writer and a good researcher. He emphasized the personal motives underlying historical events, but his moralizing was low-key compared with other historians.
marsyas of pella (fourth century). The mention of Marsyas at 20.50.4 makes it likely that his History of Macedon was a source for Diodorus, but too little remains of the work for us to be sure.
philistus of syracuse (c.430–356). Philistus’ History of Sicily covered the island’s mythical origins and took the history down to the reign of Dionysius II, so he may well have been one of Diodorus’ sources for Sicilian history.
ptolemy of egypt (367–282). The first Macedonian ruler of Egypt and founder of the Ptolemaic dynasty wrote his own account of Alexander’s eastern campaigns, in which he played up his part in them. The passages in Diodorus’ work which eulogize Ptolemy’s character (17.103.6–8; 18.14.1; 18.28.3–6; 18.33.3–4; 18.34.4; 18.86.3; 19.55.5–56.1; 19.86.3–5) depend ultimately on Ptolemy’s own work, but probably as filtered to Diodorus through another historian, and Cleitarchus is the best candidate, since he was patronized by Ptolemy.
roman historians. In our books, Diodorus’ accounts of Roman history are usually no more than brief notices of the kind he would have found in his annalistic source or sources (e.g. 16.31.7; 16.36.4; 16.45.8; 19.10.1; 19.105.5). Sometimes, they are more thorough, however (19.72.3–9; 19.76; 19.101; 20.35–6; 20.80; 20.90.3–4), and the question is from where Diodorus got his information. But early Roman historians tend to be little more than names to us, and it is impossible to tell exactly who Diodorus’ source or sources might have been. The chief possibilities are: Quintus Fabius Pictor (late third century), Lucius Cincius Alimentus (early second century), Gaius Acilius (mid second century), Aulus Postumius Albinus (mid second century), Gnaeus Gellius (late second century), and Lucius Cassius Hemina (late second century).
theopompus of chios (378–320). Among other works, he wrote a twelve-book Greek History, which was a continuation of the History of Thucydides down to 394, and a fifty-eight-book History of Philip, which, despite its title, set out to be a universal history with Philip II as its core. He was given to Herodotean digressions on topics such as ethnography and geography, and wrote in a studied, rhetorical style, which was very popular in its day. He was known for exploring the psychology and motivations of his protagonists. He was a moralizing historian, who expressly vilified statesmen and generals for their wrongdoing. Since his History of Philip is mentioned at 16.3.7, Diodorus probably made use of him for his account of Philip’s career, especially for negative stories such as 16.87.1, since Theopompus seems to have played up Philip’s flaws. Diodorus may have used him also for Sicilian affairs in Book 16 (see 16.71.3). He also wrote a monograph on the Third Sacred War—On the Funds Stolen from Delphi—and may have influenced Diodorus’ account of the war.
timaeus of tauromenium (c.350–c.260). Timaeus was exiled by Agathocles from his native city (which his father had refounded: 16.7.1) and spent much of his life in Athens, researching and writing. He paid close attention to chronology, and tried to reconcile the lists of Olympiads with those of Ephors and kings of Sparta, priestesses of Hera at Argos, and Athenian Archons. His major work was a History of Sicily in thirty-eight books, up to the year 264. In this book, he also covered Carthaginian affairs and gave a potted history of early Rome, whose rise to power he was one of the earliest historians to note. The History of Sicily became the standard work in the ancient world on the history of the western Greeks. He was the first explicitly to assess the worth of his predecessors’ efforts as historians. His work is referred to twice by Diodorus in our books (20.79.5; 20.89.5), making it clear that he was one of Diodorus’ sources for Sicilian history; in particular, Diodorus probably combined Duris’ favourable account of Agathocles with Timaeus’ hostile version. Timaeus was a moralizing historian, who used a full palette of techniques to get his points across.
zeno of rhodes (late third/early second centuries). Zeno is an obscure historian to us, but some of his work is commonly thought to lie behind Diodorus’ account of the siege of Rhodes (20.82–8; 20.91–100).
I should repeat that this is all speculation. Since the work of these historians survives only in fragments, and sometimes in very few fragments, we cannot be absolutely sure that or to what extent Diodorus drew on them. Nevertheless, scholarly consensus has settled on them as Diodorus’ likely sources for Books 16–20. The cases for Cleitarchus, Timaeus, and Hieronymus are pretty solid, but identifying the other sources involves a greater or lesser degree of guesswork. But even with these identifications, the difficulty is in deciding how much belongs to the original and how much to Diodorus.
Here I compare the names given by Diodorus with those in the definitive list of Roman magistrates: T. R. S. Broughton, The Magistrates of the Roman Republic, vol. 1 (New York: American Philological Association, 1951). Broughton’s list was drawn up from a variety of sources, both literary and inscriptional, including Diodorus. But Broughton followed the dating system invented by M. Terentius Varro, a contemporary of Diodorus, whereas (for the books translated in this volume, at any rate) Diodorus followed a different system, the origin of which is unknown. Diodorus is several years ahead of Varro (a varying number of years at different points), so that, for example, his 356/5 is Broughton’s 359.
| Diodorus | Broughton |
|---|---|
| 360/59 | |
| Cn. Genucius & L. Aemilius | Cn. Genucius Aventinensis & L. Aemilius Mamercinus |
| 359/8 | |
| Q. Servilius & Q. Genucius | Q. Servilius Ahala & L. Genucius Aventinensis |
| 358/7 | |
| C. Licinius & C. Sulpicius | C. Licinius Calvus & C. Sulpicius Peticus |
| 357/6 | |
| M. Fabius & C. Publius | M. Fabius Ambustus & C. Poetelius Libo Visolus |
| 356/5 | |
| M. Publius Laenates & Cn. Maemilius Imperiosus |
M. Popillius Laenas & Cn. Manlius Capitolinus Imperiosus |
| 355/4 | |
| M. Fabius & C. Plautius | C. Fabius Ambustus & C. Plautius Proculus |
| 354/3 | |
| C. Marcius & Cn. Manlius | C. Marcius Rutilus & Cn. Manlius CapitolinusImperiosus |
| 353/2 | |
| M. Publius & M. Fabius | M. Popillius Laenas & M. Fabius Ambustus |
| 352/1 | |
| C. Sulpicius & M. Valerius | C. Sulpicius Peticus & M. Valerius Poplicola |
| 351/0 | |
| M. Fabius & T. Quinctius | M. Fabius Ambustus & T. Quinctius Poenus Capitolinus Crispinus |
| 350/49 | |
| M. Valerius & C. Sulpicius | M. Valerius Poplicola & C. Sulpicius Peticus |
| 349/8 | |
| M. Gaius & P. Valerius | C. Marcius Rutilus & P. Valerius Poplicola |
| 348/7 | |
| C. Sulpicius & C. Quinctius | C. Sulpicius Peticus & T. Quinctius Poenus Capitolinus Crispinus |
| 347/6 | |
| C. Cornelius & M. Popilius | L. Cornelius Scipio & M. Popillius Laenas |
| 346/5 | |
| M. Aemilius & T. Quinctius | L. Furius Camillus & Ap. Claudius Crassus Inregillensis |
| 345/4 | |
| M. Fabius & Ser. Sulpicius1 | M. Valerius Corvus & M. Popillius Laenas |
| 344/3 | |
| M. Valerius & M. Popilius | C. Plautius Venno & T. Manlius Imperiosus Torquatus |
| 343/2 | |
| C. Plautius & T. Manlius | M. Valerius Corvus & C. Poetilius Libo Visolus |
| 342/1 | |
| M. Valerius & Cn. Publius | M. Fabius Dorsuo & Ser. Sulpicius Camerinus Rufus |
| 341/0 | |
| C. Marcius & T. Manlius Torquatus | C. Marcius Rutilus & T. Manlius Imperiosus Torquatus |
| 340/39 | |
| M. Valerius & A. Cornelius | M. Valerius Corvus & A. Cornelius Cossus Arvina |
| 339/8 | |
| Q. Servilius & M. Rutilius | Q. Servilius Ahala & C. Marcius Rutilus |
| 338/7 | |
| L. Aemilius & C. Plautius | L. Aemilius Mamercinus Privernas & C. Plautius Venno |
| 337/6 | |
| T. Manlius Torquatus & P. Decius | T. Manlius Imperiosus Torquatus & P. Decius Mus |
| 336/5 | |
| Q. Publius & Ti. Aemilius Mamercus | Q. Publilius Philo & Ti. Aemilius Mamercinus |
| 335/4 | |
| L. Furius & C. Manius | L. Furius Camillus & C. Maenius |
| 334/3 | |
| C. Sulpicius & L. Papirius2 | C. Sulpicius Longus & P. Aelius Paetus |
| 333/2 | |
| K. Valerius & L. Papirius | K. Duillius & L. Papirius Crassus |
| 332/1 | |
| M. Atilius & M. Valerius | M. Atilius Regulus Calenus & M. Valerius Corvus |
| 331/0 | |
| S. Postumius & T. Veturius | S. Postumius Albinus & T. Veturius Calvinus |
| 330/29 | |
| C. Domitius & A. Cornelius | Cn. Domitius Calvinus & A. Cornelius Cossus Arvina |
| 329/8 | |
| C. Valerius & M. Claudius | C. Valerius Potitus & M. Claudius Marcellus |
| 328/7 | |
| L. Platius & L. Papirius | L. Plautius Venno & L. Papirius Crassus |
| 327/6 | |
| missing | L. Aemilius Mamercinus Privernas & C. Plautius Decianus |
| 326/5 | |
| P. Cornelius & A. Postumius | P. Cornelius Scapula & P. Plautius Proculus3 |
| 325/4 | |
| L. Cornelius & Q. Popillius | L. Cornelius Lentulus & Q. Publilius Philo |
| 324/3 | |
| C. Publius & Papirius | C. Poetelius Libi Visolus & L. Papirius Cursor |
| 323/2 | |
| L. Frurius & D. Junius | L. Furius Camillus & D. Junius Brutus Scaeva |
| 322/1 | |
| C. Sulpicius & C. Aelius | C. Sulpicius Longus & Q. Aulius Cerretanus |
| 321/0 | |
| missing | Q. Fabius Maximus Rullianus & L. Fulvius Curvus |
| 320/19 | |
| missing | T. Veturius Calvinus & S. Postumius Albinus |
| 319/18 | |
| Q. Popillius & Q. Publilius | L. Papirius Cursor & Q. Publilius Philo |
| 318/17 | |
| Q. Aelius & L. Papirius | Q. Aulius Cerretanus & L. Papirius Cursor |
| 317/16 | |
| L. Plautius & M’. Fulvius | L. Plautius Venno & M’. Folius Flaccinator |
| 316/15 | |
| C. Junius & Q. Aemilius | C. Junius Bubulcus Brutus & Q. Aemilius Barbula |
| 315/14 | |
| S. Nautius & M. Popillius | S. Nautius Rutilus & M. Popillius Laenas |
| 314/13 | |
| L. Papirius & Q. Publius | L. Papirius Cursor & Q. Publilius Philo |
| 313/12 | |
| M. Publius & C. Sulpicius | M. Poetelius Libo & C. Sulpicius Longus |
| 312/11 | |
| L. Papirius & C. Junius | L. Papirius Cursor & C. Junius Bubulcus Brutus |
| 311/10 | |
| M. Valerius & P. Decius | M. Valerius Maximus & P. Decius Mus |
| 310/9 | |
| C. Julius & Q. Aemilius | C. Junius Bubulcus Brutus & Q. Aemilius Barbula |
| 309/8 | |
| Q. Fabius & C. Marcius | Q. Fabius Maximus Rullianus & C. Marcius Rutilus |
| 308/7 | |
| P. Decius & Q. Fabius | P. Decius Mus & Q. Fabius Maximus Rullianus |
| 307/6 | |
| Ap. Claudius & L. Volumnius | Ap. Claudius Caecus & L. Volumnius Flamma Violens |
| 306/5 | |
| Q. Marcius & P. Cornelius | Q. Marcius Tremulus & P. Cornelius Arvina |
| 305/4 | |
| L. Postumius & Ti. Minucius | L. Postumius Megellus & Ti. Minucius Augurinus |
| 304/3 | |
| P. Sempronius & P. Sulpicius | P. Sempronius Sophus & P. Sulpicius Saverrio |
| 303/2 | |
| Ser. Cornelius & L. Genucius | Ser. Cornelius Lentulus & L. Genucius Aventinensis |
| 302/1 | |
| M. Livius & M. Aemilius | M. Livius Denter & M. Aemilius Paullus |