‘M. Tvllivs … etiam in hoc opere [i.e. philosophia] Platonis aemulus exstitit.’ There is a fallacy underlying Quintilian's judgement here—he is not by any means at his best in this famous chapter—which is interesting in that, with very different consequences, it also underlies the almost total neglect of Cicero's philosophical works prevalent in this country in our own day. (That Cicero's philosophical works were once popular everyone knows; but many would, I fancy, be surprised to learn how much serious and scholarly attention they are still receiving in America, France, and Germany.) The fallacy which is the common basis of Quintilian's approbation and our neglect is the belief, explicit or implicit in much modern criticism, that Roman literature is to be assessed by comparison, man for man and genre for genre, with Greek. Some such comparisons can be made, and with profit for those who do not prejudge the issue of the investigation and, since the Roman writers often seem deliberately to invite such comparisons, for those who are equipped with the necessary understanding of what ‘imitation’ means in the context of ancient literature. But these comparisons are silly and fruitless when conducted with the kind of naïveté which can see in Cicero's philosophical writings only a ‘poor man's Plato’. To compare Cicero and Plato in this field is to compare incomparables. This becomes clear if we forget our presuppositions and ask, as I propose to do, (1) what was Cicero in his philosophical writings trying to do and was it worth doing, and (2) how did he set about his task, and were his methods the right ones ? Only then can we attempt, as I shall do briefly in concluding, an estimate of his achievement.