I wish Calcidius, and R.-S.'s new book, could make it out of the Classics or ancient philosophy syllabus and into philosophy of science courses or, maybe even, however briefly, into introductory physics classes, because Calcidius – exhaustively presented and contextualised in this new book – gives us such a radically contrasting vision to our own: the universe is like a city, the world is a like a great ontological lambda (that is, ‘physics’ is related to ‘theology’), and, thus, cosmological claims have ethical and political implications. Even better than texts of Aristotle, Calcidius’ commentary makes it clear what kinds of questions seventeenth-century natural philosophers knowingly bracketed in preference for a new mathematical and mechanistic methodology. R.-S.'s book builds up a portrait of an approach to the natural world strikingly at odds with the modern cosmic imaginary, one that has become so internalised that, without books like this, any ontological, epistemological or cosmological alternative is practically unthinkable.

The book begins with historiography. Wedged between Classics and medieval studies, Calcidius’ lengthy book on Plato's Timaeus has been treated either as a sourcebook of ancient philosophical fragments or as source text for the twelfth-century Renaissance, and, thus, Calcidius’ own voice has been lost. In R.-S.'s words, her goal is not ‘to find the smallest number of master sources possible’, but rather to highlight the ‘interpretation which he advances’ as well as how he structures his material (p. 217). To do this, R.-S. gives us a Calcidius at the crossroads of Christianity and the various late antique philosophical schools, a Calcidius who breathes the same intellectual air as Boethius. This is the book's first particular strength. Over the course of the volume Calcidius is compared and contrasted with Plato and Aristotle, but also with Middle Platonists (Numenius), Neoplatonists (Plotinus, Porphyry, Iamblichus), Stoics as well as the ‘Hebrews’ and Christians (Origen and Clement of Alexandria, for example): ‘It seems to make most sense to place Calcidius in an era in which Christianity was gaining decisive ground, but had not yet become so dominant and so caught up in theological polemics as to make a Latin commentary on Plato's Timaeus itself a charged undertaking’ (p. 220). And yet, R.-S. insistently argues that the commentary is not a mere hotchpotch of calqued passages from earlier philosophical and scientific treatises, but rather a work with an overarching order and aim. And so, Calcidius, in intention at least, would be doing for late antique philosophy something similar to Macrobius: acting like a bee who gathers pollen from many sources yet creates a honey with one distinct flavour (as he says in the preface to Saturnalia). And although R.-S. cannot completely overcome the commentary's Frankenstein-like nature, a text of texts sewed together at the seams, she does a brilliant job of foregrounding the persistent ‘theological’ ambitions of Calcidius or the commentary's ‘lambda effect’ (as in the opening epigram).

R.-S. also has something to say about the famously mysterious author, whom she locates in the mid-fourth century. As for Boethius, so too for Calcidius: Plato is the great master who ‘represents the culmination of all philosophy not only because he holds the truth, but also because he provides the most complete explanations of the structure of reality’ (p. 15). Indeed, ‘like Lady Philosophy … Calcidius … turns entire groups of thinkers into marauders, who got away with whatever bits of truth they could lay their hands on: “later philosophers, behaving like selfish heirs who vainly dissipate their paternal estate, carved a rich and complete doctrine up into mutilated little opinions (in mutilas opiniunculas)”’ (p. 17). Unlike Plato's ‘selfish heirs’, greedy ‘specialists’ (p. 13), Calcidius is moved by generosa magnanimitas (p. 13), an inspiration at once Christian but also deeply faithful to the vision of the Timaeus. In this way, given that god was moved to create ‘on account of his generosity’, Calcidius ambitiously established ‘a direct connection between himself and Plato’ (p. 18). Just as Timaeus was the ‘copy’ based on the ‘model’ of the Parmenides (which ‘treats the very origin of reality’, p. 13), and just as Timaeus’ speech was a copy of the kosmos, so, too, is Calcidius’ translation an image of an image of an image, but with a commentary to help compensate for the distance from the original source. I found this explanation of Calcidius’ Platonic self-understanding of his authorship very persuasive.

Situating Calcidius within the context of late antique debates and late antique philosophical curricula allows R.-S. to draw another strong conclusion: Calcidius built his commentary on the ancient division of philosophy into mathematics, physics and theology, giving us a ‘pedagogical’ commentary that ‘represents a gradual procession from the most basic and preliminary type of theoretical knowledge taught by mathematics … to physics … and all the way up to the most fundamental principles of reality’ (p. 27). This is a brilliant move, because it allows her to propose several new interpretations of the commentary. For instance, while J.H. Waszink and J.C.M. van Winden had proposed that the general outline of Calcidius’ commentary was determined by following a Platonic distinction (that is, the works of reason versus the works of necessity; Timaeus 47e), R.-S.'s pedagogical hypothesis – that the commentary is divided into I. Mathematics and the Universe (Chapters 8–118); IIa. Physics (Chapters 119–267); IIb. Theology, the principles of reality (Chapters 268–355) – helps her explain why Calcidius skips Timaeus’ opening speech, why he ignores the myth of Atlantis and why, although Timaeus in the dialogue's opening speech makes a distinction between Being and Becoming, Calcidius waits until Chapter 337 to address Form and Matter: ‘Given that in Calcidius’ view of theoretical philosophy the treatment of the principles of reality falls under the heading of theology, and theology follows upon mathematics and physics, any discussion of the implications of the distinction between Being and Becoming has to wait until the final part of the commentary’ (p. 128). It is a hypothesis with a lot of explanatory power.

This book has many virtues. It is clear, comprehensive and has up-to-date and excellent notes. It is not only the best summary of the status quaestionis of scholarship on Calcidius, but it could also be used as an introduction to ancient philosophy in general. If this period of philosophy was a kind of original scholasticism, which was codifying, commenting upon and ordering the already classic works of Plato (and his pupil) into pedagogical programmes, then Calcidius is a late antique Peter the Lombard, a pioneering figure, followed later by Macrobius, and eventually Boethius and Proclus.