Most classicists, including those specializing in ancient philosophy, will likely know at most two facts about Thrasyllus: he was the Emperor Tiberius’ astrologer and he arranged the Platonic corpus into tetralogies. Many will assume that there is not a great deal more than this to be known about him given the extant documents. For example, John Dillon’s careful and thorough survey, The Middle Platonists. 80 B.C. to A.D. 220, devotes less than a page to Thrasyllus. It will also be assumed that this is not a particularly lamentable state of affairs, since Thrasyllus is likely to have been at best a minor figure in the history of Platonism. Harold Tarrant has set out to challenge these assumptions in his latest book, Thrasyllan Platonism.
Tarrant believes that a careful study of the evidence reveals Thrasyllus to be a far more formidable figure than anyone has hitherto supposed. At the conclusion of his book he writes, “The influence of Thrasyllus, if my arguments have any credibility, would seem to have been immense. It falls into five main areas: philosophical influence upon (1) Neopythagoreanism, (2) Middle Platonism, and (3) Neoplatonic and early Christian thought; and influence upon Platonic interpretation down to our own times by means of (4) an arrangement of the Platonic corpus that survives and presents the material to us in a particular manner, giving an initial claim to authenticity to all that it contains and overwhelming suspicions of spuriousness to all that it does not contain, and (5) a text of Plato that Thrasyllus’ interpretative hand has coloured (208).”
Tarrant has not uncovered new evidence concerning Thrasyllus. Instead, he has examined with minute attention the small amount of material available and concluded that we can make a number of inferences about Thrasyllus’ thought and activity with reasonable confidence. The principal texts studied are Diogenes Laertius’ Lives and Opinions of Eminent Philosophers (3.48-66), Porphyry’s commentary on Ptolemy’s Harmonics, and Theon of Smyrna’s Mathematical Principles Useful for the Study of Plato. Proclus’ commentary on Plato’s Parmenides and Simplicius’ commentary on Aristotle’s Physics are also mined for their contributing to our understanding of Middle Platonism and Neopythagoreanism generally. All of the relevant texts are printed in Greek in an appendix.
In the first century B.C. when the influence of Academic scepticism had begun to wane, a revival of interest in dogmatic Platonism occurred. Antiochus of Ascalon can be identified as a central figure in that revival and also in the attempt to integrate Platonism with developments in contemporary and traditional philosophical schools. Both scholarship and syncretic ingenuity were at a premium in this milieu for there arose a keen interest in separating authentic from spurious Platonic works, ordering these in a perspicuous fashion, and in somehow reconciling the apparently confliciting traditions that had in time arose out of reflection upon them.
Diogenes of Laertius tells us that Thrasyllus claimed that Plato himself ‘published’ [E)
Tarrant wants to make much of Thrasyllus’ intervention in the arrangement, but he can really do no more than speculate. It would be particularly useful to know how the spuria in tetralogies IV and VII got to be included and whether Thrasyllus was responsible. All we know is that Diogenes says that Thrasyllus thought genuine all 36 dialogues in the 9 tetralogies and that he affixed the double titles to the dialogues, the name of the interlocutor and the subject.
Even assuming that the present arrangement is Thrasyllus’ and that this differs significantly from Plato’s or from someone else’s earlier than Thrasyllus, the important question is what is the rationale for the arrangement and what influence did it have on the reading of the dialogues.
According to Tarrant, the reading order was “intimately connected with Thrasyllus’ own view of Platonic philosophy (179).” Tarrant advances the intriguing suggestion that this reading order was made to accord with an interpretation of Plato’s educational theory in book 7 of the Republic (101). The first tetralogy is reasonably assumed to be an introduction to this schema. But it seems to me, without direct evidence to the contrary, quite unbelievable that tetralogies II – IX could have been thought by Thrasyllus to constitute the steps of an educational program mirroring that of the Republic. For one thing, the ‘visions of the Good’ that is said to be the theme of tetralogy III comes too early in the arrangement. For another, the ‘paradigms for teacher’ said to be the theme of tetralogies IV-V (Alcibiades I, Alcibiades II, Hipparchus, Amatores; Theages, Charmides, Laches, Lysis) does not clearly play a part in the educational system. Indeed, tetralogies VI-VII are tentatively included in this rubric as well. Thrasyllus may have had some Plato-inspired educational system in mind when making his arrangement, but it is difficult to believe that he thought that this arrangement actually represented Plato’s philosophy.
As for the influence of the arrangement, that is very difficult to know both for internal and external reasons. Even if subsequent philosophers understood and accepted Thrasyllus’ arrangement, most of them, like Plotinus, were unitarians. That is, they believed that Plato consistently taught a single ‘system’ that is more or less manifested in all the dialogues. Thus, not surprisingly, Plotinus seems to make little use of the Thrasyllan arrangement in the sense that he feels free to draw on material from all the tetralogies (including the spurious letters contained in IX) in constructing his interpretations of Plato’s doctrines. In addition, one might add a factor in the confusion not considered by Tarrant. That is, parallel to the revival of interest in Plato was the edition of the Aristotelian corpus by Andronicus of Rhodes. Henceforth, scholars could wrestle with Aristotle’s understanding of how to read Plato. And that of course included the claim that Plato had an unwritten doctrine. This putative unwritten doctrine, whether it existed or not, is fairly well explained by Aristotle and certainly does not serve as the culmination of the Thrasyllan tetralogical schema. So, anyone who took this doctrine seriously—such as Plotinus—would as a result have relied less on Thrasyllus’ interpretation, which evidently takes no account of the unwritten doctrine.
In addition to the purported influence of Thrasyllus’ tetralogical arrangement, Tarrant argues for his philosophical influence. The success of such an argument of course depends on identifying Thrasyllus’ philosophy. The only two known texts that shed any light at all on this matter are those of Theon of Smyrna and Porphyry mentioned above. Tarrant is undoubtedly correct in holding that Theon was much impressed with Thrasyllus and used his work in developing his own melange of mathematical, astronomical, and musical Platonism. I do not see much here, however, that indicates a philosopher who would inspire other philosophers. This may of course be owing to my own deficiency in appreciating this side of Middle Platonism.
Potentially more important is that passage in Porphyry in which Thrasyllus is explicitly mentioned. It is a long passage on the nature of logos (translated by Tarrant with lengthy commentary in chapter 5). Unfortunately, the reference to Thrasyllus is ambiguous. It is not clear how much, if any, of the logos doctrine being expounded Porphyry intends to attribute to Thrasyllus. Tarrant exerts considerable ingenuity in arguing that it is in fact a great deal. In addition, he argues that the epistemology that Porphyry proceeds to develop is likely to have been Thrasyllan as well. He does this despite the fact that there are no further references to Thrasyllus in the text. But this logos doctrine is in its main lines not substantially different from that of Plotinus, Porphyry’s teacher, and from Middle Platonists. Tarrant does not explain why it is plausible that Porphyry should have picked out Thrasyllus as an authority in philosophical matters. In a nicely ambiguous conclusion to the chapter on Porphyry and Thrasyllus, Tarrant says, “[Thrasyllus] seems to have had a logos-theory as important for his own thought as Philo’s [of Alexandria] logos was to his (146- 7).” Perhaps this is so. But every thinker in this age had a logos theory and would surely have regarded it as important. Tarrant adds that the epistemology discussed in Porphyry, “if it is indeed his [Thrasyllus’] was clearly a substantial contribution to the rethinking of Hellenistic epistemodlogy in a Platonist vein (my emphasis, 147).” This qualification is then omitted when Tarrant proceeds to say that “the outline of the relationship between the epistemology and the metaphysic again proves that Thrasyllus was making a considerable contribution to the Platonizing philosophy of his day…”
The question of Thrasyllan tampering with the received text of the Platonic corpus is handled by Tarrant in an interesting chapter that is all too brief. He selects the Meno and the Timaeus as examples where textual contamination might be suspected owing to doctrinal matters of importance to Platonists of the first century A.D. Tarrant recognizes that since he is dealing with a period long before that of our earliest manuscripts, no manuscript authority can be expected for claims that Thrasyllus attempted to improve upon Plato in various places. I do not doubt that someone who wrote ‘Platonic’ epistles, like perhaps Thrasyllus himself, was above a little textual tampering. The problem here, however, is that when it is possible to give an authentically Platonic interpretation of a text, it is so very hard to decide whether a reading is genuine or not. When what an editor or copyist reads is what Plato might have said, the only way to sort out the difference is with hard external evidence.
I do not think that Tarrant is finally very successful in challenging the traditional assessment of Thrasyllus. Although we may actually have a little more of his thought available to us than has been assumed and although his tetralogical arrangement may have subtly affected the way some Middle Platonists read Plato, I do not believe that a distinct version of Platonism indicated by the title of this book has actually been resurrected.