The first surviving work of Saint Augustine, Against the Academicians opens the Philosophical Dialogues of Cassiciacum, composed at the end of 386. Its main subject is the question of knowledge, dealt with by refuting the ‘Academicians’, the supporters of the New Academy who intended to propose a sceptical interpretation of Platonism. This dialogue is an exceptional testimony to the state of mind of the young Augustine, recently converted and marked by the influence of Neoplatonism, as well as a key to his forthcoming intellectual and doctrinal project. It also illustrates the critical reception of Cicero, one of the most famous defenders of the Academicians, making this work not only an important moment in Roman philosophy, but also an essential milestone in the history of ancient scepticism and beyond.