The Academica is a dialogue completed in 45 BC, near the beginning of the second of the two phases in his life when Cicero produced – broadly speaking – philosophical dialogues. The work is devoted to epistemology, and specifically the question of whether there is empirical knowledge as the Stoics defined it, an issue which had been debated by Stoics and Academics since the third century BC. There are speakers for the Stoic side, in particular Stoic epistemology as adopted by Antiochus of Ascalon (previously an Academic sceptic, who then turned to dogmatism), and speakers who represent Academic scepticism. Each side advances arguments for its position, as well as offering a historical account of the Academic tradition as they construe it (only one of them is extant in full). Cicero published the work in two editions, changing the speakers and shifting the fictional date of the dialogue from 62 or 61 BC to a time near the date of composition. Of these, the second book of the first edition in two books and part of the first book of the second edition in four books are extant. While some modification of the material beyond the necessary changes of speakers and scenery is likely, there is little reason to suspect substantial differences in subject matter between the two editions.1