 Cicero’s principal work on ethical theory, On Ends or On Moral Ends (in Latin De Finibus), offers perhaps the most vivid example of his use of the sceptical method to engage critically with questions about the nature of philosophy itself. The title abbreviates a longer Latin title (De Finibus Bonorum et Malorum) whose meaning – literally, On Ends of Goods and Evils – raises puzzles of its own (on which see Allen 2014), but refers, to simplify a little, to the question of what are the highest goods, the attainment of which will bring about a happy human life. Cicero considers three leading ethical theories of his day: Epicureanism, which proposes that pleasure is the highest good; Stoicism, which holds that virtue is not just the highest but the only good; and the theory of the so-called Old Academy, which, while including goods other than virtue within its conception of the supreme good, ranks virtue higher than the rest. The structure of the work is once again dialogical: for each theory, Cicero puts into the mouth of a proponent an exposition of that theory, followed by a critical response delivered by Cicero himself.