Michael Erler is Professor ordinarius of Classical Philology at the Julius-Maximilian-Universität Würzburg. He is the author of several books and articles on Plato, Platonism, Epicurus and the Epicurean tradition, drama, and Hellenistic and Imperial literature. Jan Erik Heßler is a Lecturer in the Department of Classics at the Julius-Maximilian-Universität Würzburg. He has published an edition of Epicurus's Letter to Menoeceus (2014), and co-edited Argument und literarische Form in antiker Philosophie (2013), as well as publishing numerous articles on the Platonic and Epicurean tradition. Federico M. Petrucci is Professor of Ancient Philosophy in Turin. His main research areas are Plato and the Platonist Tradition and his publications include the first English translation of the texts of the Platonist Taurus of Beirut (2018).

'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.' Peter Osorio, Bryn Mawr Classical Review

• Introduction Michael Erler, Jan E. Heßler and Federico M. Petrucci; 1. Xenocrates' invention of Platonism David Sedley; 2. An iconography of Xenocrates' Platonism David Sedley; 3. Arcesilaus' appeal to Heraclitus as a philosophical authority for his sceptical stance Anna Maria Ioppolo; 4. Authority beyond doctrines in the 1st century BC: Antiochus' model for Plato's authority Federico M. Petrucci; 5. Authority and doctrine in the pseudo-pythagorean writings Bruno Centrone; 6. Constructing authority: a re-examination of some controversial issues in the theology of Numenius Alexandra Michalewski; 7. Plutarch's E at Delphi: the hypothesis of platonic authority George Boys-Stones; 8. Aristotle's 'physics' as an authoritative work in early Neoplatonism (Plotinus and Porphyry) Riccardo Chiaradonna; 9. Conflicting authorities? Hermias and Simplicius on the self-moving soul Saskia Aerts; 10. Kathēgemōn the importance of the personal teacher in Proclus and later Neoplatonism Christian Tornau; 11. 'In Plato we can see the bad characters being changed by the good and instructed and purified' attitudes to platonic dialogue in later Neoplatonism Anne Sheppard.