It was just over half a century ago, in 1892, that Gaston Boissier published a discussion of the Stoic ‘martyrs’ under Nero in the second chapter of his well-known work L'Opposition sous les Cèsars. Since then two especially noteworthy studies of the ‘philosophic opposition’ in the first century A.D. have appeared in English, that of M. Rostovtzeff, The Social and Economic History of the Roman Empire (1926), pp. 108 ff., and, more recently, that of D. R. Dudley, A History of Cynicism (1937), pp. 125 ff. The story of men who maintained a critical or, at the least, independent attitude in the face of a totalitarian règime is obviously of great significance for us to-day. Theoretically, of course, the term ‘autocracy’, in its strict sense of ‘unaccountability’ of government, cannot be applied to the imperial system of the early Empire. On paper the ‘tyrants’, Tiberius, Gaius, Nero, and Domitian, no less than the ‘enlightened monarchs’, Augustus, Claudius, Vespasian, Trajan, Hadrian, and the Antonines, were delegates senatus populique Romani, chief magistrates and servants of the state. But in practice the ever-expanding range of the imperial provincia, coupled with the unceasing growth of the ‘mystical’ auctoritas bequeathed by the first Princeps to his successors, had produced an effective absolutism comparable, in many respects, to that of the autocrats or ‘dictators’ of modern authoritarian states. How did political thought and action in the Roman Empire respond to this de facto autocracy? How, above all, did they respond to its abuse? For us these are no merely academic questions. The parallelism, such as it is, between the ancient and the modern situations must serve as an excuse for presuming to rehandle a familiar theme.