Proclus’ voluminous Commentary on the Timaeus has been called with some justification “arguably the most important text of ancient Neoplatonism.” Throughout the commentary, Proclus develops his own unique theologizing philosophy of nature in a continuous dialogue with his predecessors, many of whom are quoted or paraphrased at some length. This makes the work essential reading, both for students of Proclus’ own philosophy and for those concentrating on earlier stages of the Platonic tradition. The Belgian scholar Gerd Van Riel has now published an excellent new edition in five volumes of this seminal text in the Oxford Classical Texts series.
The present edition replaces the one by Ernst Diehl, which was published in three volumes between 1903 and 1906 in the Teubner series. Diehl based his reconstruction of the manuscript tradition on his firm conviction that the Parisian manuscript C(oislinianus) 322, constituted the most reliable witness of the text. As Van Riel demonstrates at length in the introduction to his edition, Diehl got it spectacularly wrong. For a start, C is much younger than Diehl assumed. The manuscript is written in a script that seeks to imitate that of the 11th-12th century, the date that Diehl assigned to it, yet dates in fact from the 13th-14th century. Even worse, Diehl’s unwarranted reliance on C led him to disregard other manuscripts. Based on a careful examination of the existent manuscripts, Van Riel is now able to distinguish between no less than four families of manuscripts, only one of which is represented by C. All four families go back on one common archetype, which was a minuscule codex depending on one transliteration. This archetype, thus Van Riel, may even be the still existent manuscript W. Unfortunately, W is in a bad state: the original Proclean text was erased in order to re-use the parchment, but it has recently made readable again by means of UV photos and digital enhancement. All those Neoplatonic scholars who at this point start to worry whether they have built their arguments on textual sand can breathe a sigh of relief. As Van Riel opines, Diehl, notwithstanding his misguided reconstruction of the tradition, managed to produce “a very good text, with many good conjectures”, not only due to his philological competence but also due to the fact that he had inadvertently included good readings from other families in his edition via the collation of the editions of his predecessors, Grynaeus and Schneider. The latter had, for their respective editions, relied on an important branch in the manuscript tradition that Diehl had wrongly ignored.
While the technicalities of textual transmission may not be to the taste of all Neoplatonic scholars, I still recommend that anyone even mildly interested in the history of Neoplatonism read the introduction to Van Riel’s edition. From Diehl’s assumption that the whole of the transmission of the text depends for the most part on the lonely manuscript C one could easily conclude that the commentary suffered from neglect from the end of Antiquity until the 19th century. Nothing could be further from the truth. Van Riel’s discussion of the manuscripts that he has collated reveals a fascinating story of the, often quite intensive, study of Proclus’ Commentary on the Timaeus through the ages. An example in case is the Vatican manuscript H to which Van Riel assigns an important role in his edition. The manuscript was until recently dated to the 13th century, but now appears to have been written in the 12th century and eventually ended up in the hands of the great Platonist Marsilio Ficino. Van Riel aptly compares it to “an archaeological site, with different layers of activity through the ages.” Over the course of the centuries, parts of the manuscript got lost and were (partly) restored on the basis of other manuscripts, while the various correctors and annotators who worked on the manuscript all left their marks. Van Riel recounts the history of the manuscript with noticeable enthusiasm, sometimes even bringing to life the various hands at work. Take for example the case of the corrector referred to as H2, characterized by Van Riel as a “a skilled philologist, well-trained in Platonic and Neoplatonic philosophy, who had at his disposal not only H, but also another manuscript of Proclus’ commentary” and with knowledge of such arcane texts as the Chaldean Oracles and the Orphic poems. H2 appears to be identical with the corrector of a manuscript of Proclus’ Platonic Theology. Van Riel suggests, albeit cautiously, that this person may be Georgios Akropolites (1217-1282). This Byzantine intellectual, disappointed with the intellectuals of his age, had turned to the Platonic philosophers for inspiration placing himself, as he put it elsewhere, “in the company of the most divine Plato and the Muse-inspired Proclus, and even such most divinely inspired men like Iamblichus, Plotinus and the others, which I cannot enumerate now” (tr. Van Riel).
The history of the transmission of this text is not only one of scribes and correctors but also of translators. These too get their due in Van Riel’s apparatus. Modern readers of the commentary will no doubt be acquainted with the momentous French translation by A. J. Festugière and the more recent English translation by a team of Australian scholars, consisting of Dirk Baltzly, Harold Tarrant, David Runia, and Michael Share. Their translating activities inevitably forced them to face problems in the Greek text and led them to produce a number of good conjectures, which have all found their way into Van Riel’ apparatus. Yet, they are not the first to have done so. Van Riel calls attention to a Latin translation of the text, now in the library of Leiden University, by an anonymous “skilful medieval translator”, who “follows the argument and wants to render it in a comprehensible way, and who has been correcting the text throughout”, both on the basis of a witness of the family stemming from H and by making his own conjectures.
This fresh reconstruction of the manuscript tradition in combination with a meticulous study of the history of the scholarship on the Commentary yield at times significant results. An example in case is Van Riel’s emendation of In Tim. ii. 274.16-17 (in this edition; i. 393.31-394.2 ed. Diehl). The sentence occurs in a passage in which Proclus criticizes his predecessor Atticus. Diehl, who as always follows the reading that he finds in C, reads the sentence as follows: Τρίτον τοίνυν, ὅτι οὐδὲ ὁ ποιητής, ὃν παραλαμβάνουσιν ἀρχήν, προσήκει τῷ Πλάτωνι· Thus, according to the text of both C and Diehl, Proclus’ point would be that Atticus’ identification of a divine maker with the principle of the cosmos is not in keeping with what Plato actually says in the Timaeus. Des Places adopted this reading in his edition of the fragments of Atticus (see fr. 28). It is, though, not without problems, as the afore-mentioned Latin translator was already aware when he tried, albeit not very convincingly, to translate the problem away by tacitly changing the singular ποιητής into a plural and by rendering it as poete. Hence according to our anonymous translator, it is not Atticus but the poets who disagree with Plato about the principle. Centuries later, the Australian translators also felt that something is amiss with the text. In a footnote to the translation, Michael Share gives a precise analysis of the problems involved with the reading of Diehl. Turning for inspiration to an alternative manuscript reading that he finds in Diehl’s apparatus, he suggests that the mysterious maker (ποιητής) was in fact a corruption of εἴποι ἄν τις, translating the sentence as follows: “Thirdly, one would go as far as to deny that any of the principles they assume is in Plato.” While Share’s emendation is now rejected by Van Riel, it informs his own emendation of the text: Τρίτον τοίνυν, ὅτι οὐδὲ ὁποία τις <οὖν>, ὃν παραλαμβάνουσιν ἀρχήν, προσήκει τῷ Πλάτωνι. Thus, on this reading, none of the principles that Atticus and his followers assume can actually be found in Plato. In all three cases, the reference to the maker evaporates, something that is as relevant for the study of Proclus as for that of Atticus, if not more so.
Unlike Diehl, Van Riel has articulated his text into paragraphs, which certainly improves its readability. It is perhaps also with the readability of the text in mind that in case of a gap in the transmitted text—the transmission of book V in particular is rather patchy—Van Riel tends to offer a tentative construction. He even does so in cases where some of his predecessors have felt that such a speculative conjecture does little to improve our understanding of the text.  Personally, I would be a bit hesitant to fill in some of these lacunae. This, however, is a matter of taste rather than of criticism: Van Riel clearly indicates that we are dealing here with tentative reconstructions and his informative apparatus, with a clear indication of the number of missing letters and an overview of the suggested conjectures, opens up the possibility for future students of the text to indulge in speculations of their own.
In conclusion, some 120 years after Diehl published his edition, we now have a much improved version of the text, one that is based on a completely new and convincing reconstruction of the manuscript tradition and that incorporates centuries of scholarship and philological acumen. The merits of this edition will no doubt become more evident when colleagues will start to use it as the basis for their own research into the Platonic tradition.
 D. Baltzly & H. Tarrant, in: H. Tarrant, Proclus: Commentary on Plato’s Timaeus: Volume 1, Book 1: Proclus on the Socratic State and Atlantis, Cambridge 2007: 1.
 A. J. Festugière, Proclus, Commentaire sur le Timée, 5 volumes, Paris 1966-1968; D. Baltzly et al., Proclus, Commentary on Plato’s Timaeus, 6 volumes, Cambridge 2008-2017.
 On this passage, cf. also G. Van Riel, ‘Proclus, Porphyry Atticus and the Maker. Remarks on Proclus, In Ti. II, 1.393.31–394.5 (Atticus, Fr. 28)’, CQ 68, 2 (2019), 681-688.
 Cf. H. Tarrant, Proclus, Commentary on Plato’s Timaeus (volume 6). Book 5: Proclus on the Gods of Generation and the Creation of Humans, Cambridge 2017: 61 n. 77: “The supplement provided by Diehl and Festugière is insecure and does not add clarity to the argument. I believe it best to leave a gap.” (commenting on In Tim. iii. 182.10-14 Diehl = v. 27.3-7 Van Riel).