The increased attraction exercised by non-Greek wisdom on philosophers of the Roman Empire has often been remarked upon. Greek philosophy had been fascinated by the East at least from Plato onwards, but the range of foreign peoples that drew interest clearly started to increase in the late Hellenistic and early Imperial period, with philosophers such as Plutarch and Numenius referring to Egyptian and Oriental cults as containing profound knowledge. Usually explained as the result of the expansion of geographical horizons in the wake of Hellenisation and Roman conquest, the phenomenon is clearly also part of the process of the opening up of philosophy to other sources of authority in this period, which I have sketched in the introduction.

The importance of this wider philosophical context has recently been underscored by G. Boys-Stones, who has shown that the interest in ‘barbarian wisdom’ betrays less a specific respect for all things foreign than an increased authority attributed to antiquity in general, Greek and barbarian. He argues that the Stoic philosopher Posidonius (c. 135–55 bc) was the first to attribute specifically philosophical knowledge to the first age of man, and not just a mere unreflective practice of virtue. The only evidence for Posidonius’ views in this respect is Seneca's ninetieth letter to Lucilius. Although the letter is difficult to interpret, two elements emerge from it that can be traced in later expositions of ancient wisdom. First, for Posidonius, human culture was created on purpose by lawgivers in line with philosophical thought when the Golden Age came to a close. Sages invented the arts to make life amenable once vice had disrupted the harmony with nature that characterised that age of felicity. Human culture thus has an ambivalent nature: created by sages it contains philosophical knowledge, but at the same time it marks the end of the Golden Age. Secondly, such sages remain active as benefactors of mankind for a long time after the close of the Golden Age – the last one mentioned by Posidonius (as summarised by Seneca) is Democritus (Ep. 90.31–2). This suggests that there may always be sages and philosophers who can adjust culture so as to bring it more in line again with nature and philosophy (both being basically identical in a Stoic perspective). This theory accounts for attempts to find philosophical knowledge in ancient traditions, Greek, Roman, and foreign. Until the late first century ad, G. Boys-Stones suggests, the idea was only adopted by Stoics, most notably by Cornutus, the Stoic teacher of Nero, in his On the Nature of the Gods. Shortly afterwards the theory passed into Platonism, where it led to the view that the leading philosophers of the past, such as Pythagoras and Plato, were seen as having rediscovered ancient wisdom and expressed it in rational discourse.