Agonistes comprises a collection of essays presented by his friends and colleagues to Denis O'Brien, former Directeur de recherché at the Centre Nationale de Recherché Scientifique, representing the full range of his scholarly interests in the field of ancient philosophy, from the Presocratics, through Plato, Aristotle and Hellenistic philosophy, to Plotinus and later Neoplatonism. The honorand himself leads off with a stimulating Apologia, sketching the development of his scholarly interests and dwelling on the issues that have chiefly concerned him. The contributions then follow in chronological order, under four headings: I From the Presocratics to Plato (Frère, Brancacci); II From Plato to the Stoics (Brisson, Casertano, Dixsaut, Kühn, McCabe, Narcy, Rowe, Goulet); III Plotinus and the Neoplatonist Tradition (O'Meara, Sakonji, Gersh, Steel, Dillon, Smith); IV Saint Augustine and After (Pépin, Rist, Brague/Freudenthal). They comprise a significant representation of the most distinguished scholars both on the continent and in the British Isles, and fairly represent the wide influence which Denis O'Brien has had on his contemporaries. The volume includes also a full bibliography of O'Brien's works.