[Authors and titles are listed at the end of the review. Disclaimer: I avoid comment on Chapter 7 due to a professional connection.]
This volume follows recent work on the concept of authority in ancient Greek and Roman philosophy, and it sheds light on the Platonic tradition by examining different conceptions of authority from Plato’s immediate successors to late Neoplatonists. In their Introduction, the editors stress that by defining the specific grounds and function of a thinker’s conception of authority, a discontinuous but more honest history of the long tradition of Platonism can be told. Such prefatory comments give the impression that the volume’s contributions will not be well integrated. But, except for a lack of cross-references between them, the chapters are on the whole complementary and benefit from being published together. This is particularly true of those chapters that deal with conceptual issues concerning the grounds or nature of authority (Petrucci, Boys-Stones, Tornau, and, to a lesser extent, Aerts). Those chapters that attend more to the deployment of authority for polemical or legitimizing purposes (Sedley’s two chapters, Ioppolo, Centrone, Michalewski, Chiaradonna, and Sheppard) ought to be read in light of the former set. While chapters are arranged chronologically, this rough division structures my discussion below, starting with the conceptual set.
Petrucci raises a call to action, for discussions of Antiochus’ allegiance to Plato to move beyond the problem of whether his doctrines are more Platonic or Stoic. Petrucci looks instead at Antiochus’ own conception of a Platonic system. For Antiochus, the Platonic tradition is less a store of preserved doctrines than a family linked by resemblances: slight changes in a relative’s appearance do not remove them from the family (e.g., Aristotle and Theophrastus), and we can recognize that a relative belongs to the family even when they try to hide their resemblance (e.g., Zeno). For this reason, Peripatetics and Stoics can change Plato’s system without destroying it. Still, Plato is “the fundamental philosophical authority” (98) in virtue of his role as the founder of his Academic system. Petrucci notes (91 n. 12) that he differs in this respect from Georgia Tsouni, who holds that for Antiochus Plato offers only “the starting points of all subsequent philosophical developments.” Perhaps, though, the fact that Antiochus saw the Old Academy as liable to correction speaks in favor of Tsouni (Ac. 1.43). At least, Petrucci and Tsouni’s views may be compatible: Plato has the greatest authority, but authority, as a reason for belief, is defeasible.
In contrast to Petrucci, Tornau explores the other side of possible attitudes towards Plato’s authority, in the context of the “teacher” (kathēgemōn) in Proclus (and Simplicius et al.). Proclus refers not only to his personal instructor, Syrianus, but also to Plotinus and even Plato as kathēgemōn. Tornau shows that Proclus adapts Plotinus’ metaphysics of contemplation (Enn. 3.8) to a flexible, triadic model of pedagogy: learner, exegete, author (cf. in Prm. 976.12–20 and 1022.24–1023.4; PT 1.10). In different contexts, an exegete like Syrianus or an author like Plato can play the role of kathēgemōn, in the way that a middle term may connect intellectual to psychic reality, or psychic to physical reality. By extension, the same person can be a kathēgemōn in different aspects, in their capacity as commentator on a divine author or as one who has personally grasped the intelligible realm. Behind this polyvalence, Tornau suggests, is the myth of the Phaedrus, where Zeus is both supreme god and the hēgemōn of the divine chorus (Phdr. 246e). The implications of Tornau’s account – that Plato’s authority stems from his intellectual insight, an insight which is available to later commentators – are important and speak to the concerns of Petrucci (cf. 223) and Boys-Stones (cf. 218). Of the others, Tornau can be read alongside Michalewski – on the appeal to triadic authorities in Numenius and Proclus – and Aerts (cf. 224), who discusses Hermias’ appeal to the principle of the mean between contraries.
Aerts’ starting point is that the polysemy of symphōnia, an important concept among Neoplatonist commentators, has led to confusion in modern studies. By comparing how Hermias and Simplicius treat Aristotle’s criticisms of Plato’s self-moving soul (Arist. Phys. 8.5; De an. 1.3; cf. Pl. Phdr. 245c5–d7; Leg. 10.894b–896c), Aerts distinguishes a weak and strong notion of harmony between Plato and Aristotle. Hermias finds a weak symphōnia in that Aristotle ought to admit that the (rational) soul is self-moving, since it is also an Aristotelian principle that changes between contraries require a middle term (cf. Phys. 227a7–226b32); applying this principle to motion, self-moving soul mediates between unmoved Intellect and externally moved bodies (in Phdr. 110.21–111.3). Simplicius’ strong harmony rests on the argument that Aristotle and Plato use “motion” (kinēsis) in two senses, each appropriate for their respective methods: since Aristotle proceeds from what is evident to the senses, he uses the ordinary sense of motion as limited to physical motion (in Phys. 1248.21–1249.6), whereas in Plato “motion” refers to every kind of change (metabolē). Aristotle therefore criticizes Plato’s apparent, not actual, position. Aerts’ distinction is also helpful when reading Chiaradonna on Porphyry’s friendlier (than Plotinus’) attitude towards Aristotle’s Physics.
Of the more applied chapters I limit my remarks to Centrone, Ioppolo, and Sedley’s two papers. Centrone pursues a series of questions about the choice of pseudonyms in the Doric Pseudopythagorica, treatises likely dating from between the first centuries BCE and CE. Why is ‘Pythagoras’ avoided? Why write under such obscure names as ‘Aresas’, ‘Brotinus’, and ‘Callicratidas’? And why is ‘Archytas’ so predominant? Centrone’s answer to this last question is most relevant here: Archytas is the ideal cover for giving Platonic doctrines a Pythagorean pedigree (cf. Archytas’ letter at DL 8.79–80). But in each case, Centrone shows that Hellenistic research put constraints on what pseudonyms it made sense to choose.
Ioppolo (who died in 2020: the volume is dedicated to her memory) argues that Arcesilaus cited the historical Heraclitus in his anti-Stoic polemics. Here she sets herself against those who read the names of Parmenides and Heraclitus – listed by Plutarch as authorities to whom Arcesilaus appealed (Adv. Col. 1121F–1122A) – as mere allusions to Plato’s Parmenides and Theaetetus. She starts by outlining Cleanthes’ Heraclitean exegesis of Zeno’s definition of the soul as “perceptive exhalation” (SVF I.519): the soul is impressionable because it is constantly renewed by external inflows, like a river (cf. Heraclitus B12 DK). She plausibly argues that Arcesilaus is the source for Plutarch’s criticism of this definition (Comm. not. 1084F–1085A) and that he re-applied Socrates’ argument against the flux theorists in Theaetetus. Less persuasively, Ioppolo further maintains that Arcesilaus is behind Plutarch’s quotation of Heraclitus in the course of his defense of Socratic inquiry: “I have examined myself” (edizēsamēn hemeōuton, B101 DK = Adv. Col. 1118C). Whether referring to a completed inquiry or an abandoned one, the aorist tense of Heraclitus’ dictum makes it an unsuitable slogan for Arcesilaus.
In the first of his two chapters, Sedley offers an exciting reconstruction of Xenocrates’ Platonism. For Sedley, it consisted of mapping the One-Dyad pair onto a sempiternalist interpretation of the Timaeus. It also included the use of Phaedrus to interpret/correct the Timaeus in light of contemporary criticisms, namely, by expanding the Timaeus’ two-world ontology to a three-world ontology (the levels being below, within, and beyond heaven). This is held together by a doctrine of daemons acting as intermediaries (also as described in Phaedrus). The prominence of the Phaedrus myth in this reconstruction is unexpected, and arguing for it is Sedley’s primary contribution. However, it is unclear to me how Xenocrates is supposed to have read Phaedrus in light of the Timaeus: sometimes the myth of Phaedrus is used to “elaborate” (24) or “constrain and supplement” (29) the Timaeus, while other times it is taken more strongly to “modify the Timaeus” (27). These are very different attitudes and have different implications for Xenocrates’ reading of Plato. Sedley also elides the difficulty of harmonizing the evidence for Xenocrates’ integration of the two-world and three-world metaphysics: in Aëtius 1.7.30 (16) the monad both rules in heaven and is called intellect, while in Sextus M 7.147–9 (22–23) intelligible substance is beyond heaven.
Sedley supports his interpretation of Xenocrates’ Platonism by appealing to the Naples Mosaic of the Philosophers, arguing that its celestial sphere depicts the circuits of the 11 gods of the Phaedrus. His interpretation of the mosaic is then built up to an incredible level of detail in his companion chapter. He offers a comprehensive interpretation of the scene’s seven figures, identifying them, from left to right, as Archytas, Speusippus, Plato, Timaeus, Eudoxus, Xenocrates, and Aristotle. Except for Timaeus, his identifications are not new, but the impressive feat of his chapter is to explain nearly every element in the scene, especially what he takes to be identifying signs above six of the figures. What emerges is a depiction of Plato, from the exedra in the Academy just before his death, teaching Xenocrates the celestial motions underlying the Phaedrus myth. All of Sedley’s identifications are inspired – the withered branch of Plato’s plane tree representing Speusippus must, or ought to, be right. But they are not all compelling. For instance, Sedley takes the sundial on the central column to mark the figure below it as Eudoxus; this is taken to be an “Arachne” sundial, which Eudoxus invented (Vitr. 9.8.1). But we do not know what made the Arachne unique, and the one depicted looks like an ordinary spherical or conical sundial. Also, the pairing of a sundial behind a griffin-legged schola seems to have become typical by the first century BCE (cf. the Triangular Forum in Pompeii, CIL X 831). The pairing, whether the product of Hellenistic / Republican tastes or original to the Academy, speaks against the sundial as a symbol for an individual.
The volume is a success. It addresses problems about conceptions of authority, a topic that is rightly seeing growing interest by historians of philosophy, in the diverse yet cognate contexts of the Platonic tradition. Its contributions are engaging and provoke thought on a wide range of material. I happily await the editors’ planned companion volume on the Epicurean tradition (ix). Typos are minimal.
Authors and titles
Michael Erler, Jan Erik Heßler, and Federico M. Petrucci, Introduction
1. David Sedley, Xenocrates’ Invention of Platonism
2. David Sedley, An Iconography of Xenocrates’ Platonism
3. Anna Maria Ioppolo, Arcesilaus’ Appeal to Heraclitus as a Philosophical Authority for His Sceptical Stance
4. Federico Petrucci, Authority beyond Doctrines in the First Century BC: Antiochus’ Model for Plato’s Authority
5. Bruno Centrone, Authority and Doctrine in the Pseudo-Pythagorean Writings
6. Alexandra Michalewski, Constructing Authority: A Re-examination of Some Controversial Issues in the Theology of Numenius
7. George Boys-Stones, Plutarch’s E at Delphi: The Hypothesis of Platonic Authority
8. Riccardo Chiaradonna, Aristotle’s Physics as Authoritative Work in Early Neoplatonism: Plotinus and Porphyry
9. Saskia Aerts, Conflicting Authorities? Hermias and Simplicius on the Self-Moving Soul
10. Christian Tornau, Kathēgemōn: The Importance of the Personal Teacher in Proclus and Later Neoplatonism
11. Anne Sheppard, ‘In Plato we can see the bad characters being changed by the good and instructed and purified.’ Attitudes to Platonic Dialogue in Later Neoplatonism
 Jan Opsomer and Angela Ulacco, “Epistemic Authority in Textual Traditions: A Model and Some Examples from Ancient Philosophy,” in Shaping Authority: How Did a Person Become an Authority in Antiquity, the Middle Ages and the Renaissance?, ed. Shari Boodts, Johan Leemans, and Brigitte Meijns (Leiden: Brill, 2016), 21–46; Jenny Bryan, Robert Wardy, and James Warren, eds., Authors and Authorities in Ancient Philosophy (Cambridge: Cambridge University Press, 2018) [= Bryan et al. (eds.) 2018].
 Georgia Tsouni, “The Emergence of Platonic and Aristotelian Authority in the First Century BCE,” in Bryan et al. (eds.) 2018, 269.
 On a Middle Platonist predecessor of this unrestrictive notion of epistemic authority, see Boys-Stones’ chapter in this volume and its companion piece: George Boys-Stones, “Numenius on Intellect, Soul, and the Authority of Plato,” in Bryan et al. (eds.) 2018, 184–201.
 For exactly what names/treatises he has in mind, see a companion paper of his, “The Pseudo-Pythagorean Writings,” in A History of Pythagoreanism, ed. Carl Huffman (Cambridge: Cambridge University Press, 2014), 319 n. 17.
 Archytas is associated with 17 titles in Holger Thesleff, An Introduction to the Pythagorean Writings of the Hellenistic Period (Åbo: Åbo Akademi, 1961).
 The similarity between the mosaic’s schola-sundial and those in the Triangular Forum was already noted by Antonio Sogliano, “L’Accademia di Platone,” Monumenti Antichi 8 (1898): cols. 406–7.