Aristocles of Messene is an extremely important source for understanding the philosophical thought of early Pyrrhonism. But so far his polemical attitudes have discouraged scholars from taking seriously the extant fragments of his work and at present he is still an obscure figure. In this book Dr Chiesara shows Aristocles to be an erudite, acute, and faithful representative of the Aristotelianism of the first century AD. He is revealed as an accurate historian and trustworthy reporter of the major trends of first century philosophical thought - including Platonism, Stoicism, Pyrrhonism, Protagorism, Epicurism, and Eleatic and Cyrenaic philosophies - and to offer precious additions to the history of ancient philosophy, in particular to the reconstruction not only of early but also of late, namely Aenesidemean, Pyrrhonism. His exhortative aim and his polemical verve make his On Philosophy an interesting and amusing read for specialists and non-specialists alike.