Brad Inwood is University Professor of Philosophy and Classics at the University of Toronto. He is the author of numerous works, including Seneca: Selected Philosophical Letters (2007), Reading Seneca: Stoic Philosophy at Rome (2008) and The Poem of Empedocles, the editor of The Cambridge Companion to the Stoics (Cambridge University Press, 2003) and co-translator (with Miriam Griffin) of Lucius Annaeus Seneca: On Benefits (2011). Raphael Woolf is Reader in Philosophy at King's College London. He is the author of many articles on Plato, Aristotle and other aspects of Greek and Roman philosophy and also the translator of Cicero: On Moral Ends (with Julia Annas, Cambridge University Press, 2001) in the Cambridge Texts in the History of Philosophy series.