In his digression on the Gauls in Book 6 of the Gallic War, Caesar includes a portrait of the Druids (BGall. 6.13.3 sed de his duobus generibus [sc. quae aliquo sunt numero atque honore] alterum est druidum) and their public roles first and foremost in religious and legal affairs (6.13.4–5 illi rebus diuinis intersunt, sacrificia publica ac priuata procurant, religiones interpretantur … fere de omnibus controuersiis publicis priuatisque constituunt), not forgetting their philosophical doctrine (6.14.6 multa … disputant et iuuentuti tradunt). He emphasizes the strictly oral form their teaching takes (6.14.4), how ‘they do not deem it appropriate to commit it [their learning] to writing even though in almost everything else, in public and private affairs, they resort to Greek writing (neque fas esse existimant ea litteris mandare, cum in reliquis fere rebus, publicis priuatisque rationibus Graecis litteris utantur)’,Footnote ¹ about the reasons for which he then proceeds to speculate (6.14.4):

Three circumstances render this mini-digression peculiar: First, Caesar leaves no doubt that he adduces his own speculation as to their reasoning (id mihi … instituisse uidentur). This is all the more noteworthy as he is notoriously sparing of any such authorial self-reference other than for the purpose of cross-referencing (which he does frequently); and he is even more sparing in referring to himself in the first-person singular. In fact, this is the only instance in the Bellum Gallicum.Footnote ³ Second, given how broad-brushed is his sketch of the Druids, the sheer length of this explanation appears out of proportion: in fact, the summary of the Druidic doctrine (quoted below) is not afforded more space.Footnote ⁴ Lastly, when Caesar applies this knowledge to many who as a rule rely on writing rather than memory (quod fere plerisque accidit), one could wonder on what grounds this generalization rests.

All three aspects (the last-mentioned being most significant) combine to ‘signpost’ the text upon which Caesar's generalization is based: Plato's Phaedrus.Footnote ⁵ His discussion of memory and writing is clearly taken thence (275a2–5, with passages from Caesar in square brackets):

While Caesar cannot claim, as Cicero does (De diu. 1.61), to render uerba ipsa Platonis, in two instances he comes close to translating (μνήμης ἀμελετησίᾳ: minus memoriae studere; διὰ πίστιν γραφῆς: litteris confisos); one might also want to notice how the first two words in the first expression phonetically mimic the Greek (just as Caesar seems to do elsewhere in an adaptation of a Thucydidean expression).Footnote ⁶ More generally, however, the thematic and structural parallels are striking, not least in the explanations of the memory impairment, both of which, introduced by ἅτε there and ut here,Footnote ⁷ contrast external help to one's own (internal) effort (note in perdiscendo).Footnote ⁸ Closer inspection reveals further echoes: first, his expression litterarum praesidium is all but unparalleled; the TLL knows of one more fourth-century instance.Footnote ⁹ An obvious military metaphor (as Julian's use seems to confirm), it may be owed to Plato's repeated observation that a word, once written, would be ‘unable to either defend or help itself’ (αὐτὸς γὰρ οὔτ᾽ ἀμύνασθαι οὔτε βοηθῆσαι δυνατὸς αὑτῷ).Footnote ¹⁰ Plato's second cause for concern about the danger of writing—that, ‘once written down, every word could be bandied about everywhere, amongst those interested just as much as amongst those whom it behoves not’ (ὅταν δὲ ἅπαξ γραφῇ, κυλινδεῖται μὲν πανταχοῦ πᾶς λόγος ὁμοίως παρὰ τοῖς ἐπαΐουσιν, ὡς δ᾽ αὕτως παρ᾽ οἷς οὐδὲν προσήκει, 275e1–2)—is the first reason Caesar gives as to why the Druids do not write down their teachings. But Plato's chiefly hermeneutic concern—that the written word will be less meaningful when it circulates indiscriminately—has been sharpened by Caesar to indicate a classist anxiety among the Druids that their privileged teachings will be transmitted to the masses (quod neque in uulgum disciplinam efferri uelint). Third, the Druids’ preference for discussion of philosophical issues in teaching the next generation—multa praeterea de sideribus … disputant et iuuentuti tradunt—echoes Socrates’ reaffirmation of the superiority of the dialectical method in teaching (276e–277a):

But the perhaps most cogent additional reason for a well-read reader to think of the Phaedrus is the theory of metempsychosis that Caesar presents as the first and foremost tenet of the Druids’ philosophical doctrine with the help of a memorable instance of wordplay (6.14.5–6):

Socrates had developed this belief in his final speech on love, the imaginative palinode. Whichever soul, he claims, fails to maintain its wings will grow heavy and fall down to earth and into a body of a human being (Pl. Phdr. 243e7–257b6).Footnote ¹³ After a first lifetime and a subsequent existence under the earth or up in the skies, they are given another life-circle (249b4–7):

It seems, then, a rather felicitous coincidence that Graecae litterae are mentioned just where Caesar engages with Plato's Phaedrus in such various forms. If one hesitates to credit coincidence with such felicity, one could postulate that ‘Greek letters’ or, rather, ‘Greek literature’ (cf. Cic. Verr. 4.106 opinio, iudices, quae constat ex antiquissimis Graecorum litteris ac monumentis) serves as another and perhaps more traditional signpost than the one discussed above.

I have referred above to the ‘well-read reader’, who may be said to be an approximation to the construct of the ‘ideal reader’, whom studies of reader-response and narratology have defined as being able to ‘understand perfectly and approve entirely every authorial word or intention’.Footnote ¹⁵ While it seems doubtful that Plato's discussion of writing and memory was as well known towards the end of the Republic as Quintilian's passing remark suggests it was 150 years later,Footnote ¹⁶ there was at least one man among Caesar's contemporaries who was decidedly familiar with the dialogue. As will turn out, he was not just the ideal reader but, I should like to suggest, the ‘intended reader’ of this passage too.Footnote ¹⁷

Cicero admired the Phaedrus and referred to and quoted from it repeatedly in his early philosophical dialogues.Footnote ¹⁸ As recently as 55, he had pointed to it as the model for his own treatise De oratore (1.28): cur non imitamur, Crasse, Socratem illum, qui est in Phaedro Platonis? nam me haec tua platanus admonuit … ‘Why don't we, Crassus, imitate the famous Socrates, as he is presented in Plato's Phaedrus? For this plane-tree of yours reminds me …’. Caesar, in turn, not only read Cicero's chef-d’œuvre; he also responded to its view on Latinitas as developed in the third book by offering an alternative which he presented in his treatise De analogia, most probably written in 54 and pointedly and mischievously dedicated to Cicero.Footnote ¹⁹ Third, the place of Caesar's allusion to Plato had especial significance for Cicero as well, since the Aeduan Druid Diviciacus had stayed with him in 61 b.c.e.Footnote ²⁰

By weaving parts of the Phaedrus into his digression on the Druids, Caesar shows himself to be as well-versed as Cicero, Platonis aemulus (Quint. Inst. 10.123; cf. Quintus Cicero, Comment. pet. 46), in the dialogue the latter had most recently chosen for his model. This kind of acknowledgement, challenge and one-upmanship ties in neatly with a perhaps lifelong shared interest and rivalry in intellectual matters that more often than not led to disagreements.Footnote ²¹ But there may be more: Cicero, who would write about learning from Diviciacus of the Druids’ prophetic powers,Footnote ²² would have remembered too that Plato mentions a prophetic oak tree in that very passage (Phdr. 275b5–8): οἱ … ἐν τῷ τοῦ Διὸς τοῦ Δωδωναίου ἱερῷ δρυὸς λόγους ἔφησαν μαντικοὺς πρώτους γενέσθαι. τοῖς μὲν οὖν τότε … ἀπέχρη δρυὸς καὶ πέτρας ἀκούειν … ‘Those at the shrine to Zeus in Dodona said that an oak's words were the first to be prophetic. To those men back then it sufficed to listen to an oak and a rock.’ This is noteworthy because the Romans made an etymological connection between δρῦς and Druid, as Pliny shows (HN 16.249):

Whether or not Lucan alludes to this connection (Dryadae … nemora alta remotis incolitis lucis, 1.451–4), his late antique scholiast certainly knew (Comment. Lucan. 1.453) that ‘the Druids are the philosophers among the Gauls, named after trees, as they inhabit remote woods’ (sunt autem druidae philosophi Gallorum dicti ab arboribus, quod semotos lucos incolant). And so, I should like to suggest, did Caesar; and Cicero.

For Caesar trusted that a reference in his portrait of Druids to a canonical text wherein prophetic oak trees figured would not be lost on Cicero; more, he may have hoped that his intellectual peer would appreciate the sophisticated play. It is then easy to see why, despite their fundamental political disagreement, Cicero would, after a visit of the dictator in 45, exclaim (Att. 13.52) ‘that a visitor of mine could be so onerous and yet not disagreeable’ (o hospitem mihi tam grauem ἀμεταμέλητον!). For he and his onerous guest had ‘talked about nothing serious but literary matters aplenty’ (σπουδαῖον οὐδὲν in sermone, φιλóλογα multa). Perhaps the Phaedrus was among the topics they discussed.Footnote ²⁴