This paper places Diodorus Siculus’ description of Scipio Aemilianus’ embassy to Ptolemaic Alexandria and Egypt (33.28b) within the context of his historiographical aims for the Bibliotheke as a unified narrative of history’s lessons as well its more contemporary political ramifications. The surviving ancient sources which mention this Roman diplomatic tour to Egypt deliberately contrast the obese and effeminate Ptolemy VIII with the vigorous and dynamic Scipio (Plut. Mor. 200F, 777A; Athen. 6.273a, 12.549d-e; Justin 38.8.8), and several scholars have suggested that the Histories of Posidonius may have been the common origin of this juxtaposition of base Eastern tryphē and upright Roman mos maiorum (Jaehne 1983, Heinen 1983, Malitz 1983, Gruen 1984, Yarrow 2006).
It has long been thought (e.g. Strasburger 1965) that Posidonius was the chief source of Diodorus’ book 33, but recently, scholars have used more caution, recognizing that the later historian was quite capable of modifying and refocusing material from his sources (e.g. Brunt 1980, Sacks 1990, Rubincam 2018). Although Diodorus does begin by contrasting the luxury of Ptolemy with the abstemious Romans, the subsequent narrative shows interest in themes which regularly preoccupy the historian throughout the Bibliotheke in sections not under the shadow of Posidonius. Aemilianus and the Romans are portrayed as historical investigators whose journey to see the real thaumata of Egypt yields the same observations about the country’s geographical advantages as the Bibliotheke’s treatment of Egypt in book 1 (29-31). Egypt had been one of history’s greatest powers under the ancient pharaohs who properly utilized its geography (1.69.5-6, see Muntz 2017), but according to Diodorus, the upright institutions that produced such remarkable kings were abandoned by the Ptolemies (1.95.6), a sentiment shared by the ambassadors, who conclude their investigation by noting that “a very great power could be built there, if this kingdom should ever find rulers worthy of it” (trans. Walton). The text goes on to report that after leaving Egypt Aemilianus’ entourage traversed nearly the whole world (τὰ πλεῖστα μέρη τῆς οἰκουμένης ἐπῆλθον) settling disputes, renewing alliances, and in general enhancing their city’s hegemony with good-will (eunoia), harkening back to the euhemerized culture-heroes of the first books of the Bibliotheke (see Sulimani 2011). Aemilianus and his retinue are presented as a paradeigma of the historical truism found throughout Diodorus’ work that an empire is only secured by fostering eunoia, in contrast with the tyrannical lawlessness regularly displayed by various Ptolemies.
Writing in the 30s B.C., Diodorus witnessed the increasing involvement of the Romans in Ptolemaic dynastic affairs, culminating with the support of Cleopatra VII by both Julius Caesar and later Marc Antony. Caesar’s famous expedition up the Nile may have contributed to Diodorus’ emphasis on Aemilianus’ journey, but it is important to note that although Ptolemy was keen to show his guests around Alexandria, he soon fades into the background as if left behind in the palaces of the city while the Romans govern in his stead by their conventus. The episode as a whole offers two opposing models of rule: Diodorus’ vision of old-fashioned Roman justice (cf. Diod. 29.10, 32.4.4) and Ptolemaic tyrannical luxury. Since Diodorus elsewhere attributed the degradation of Roman virtue to the infiltration of tryphē (37.3), it is tempting to read Aemilianus’ visit in antithesis to Antony’s relationship with the last monarch of the Ptolemaic kingdom. Diodorus is able to adapt the juxtaposition of the king and the Roman embassy to his larger historiographical themes by making Aemilianus not simply a model of Roman virtue, but also an astute pupil of history who understands the value of inquiry, experience, and the profit of euergesia, while at the same time pointing his audience away from the allures offered by the tyrannical life, poignantly typified by the Ptolemaic house.
Principles and Practices of Greek Historiography