Augustine's identification of the Stoic therapy of passions (apatheia) as moderation (metriopatheia) has long been a focus of controversy. This article examines the theoretical foundation for Augustine's comments on the relationship between apatheia and metriopatheia in the Stoic and the Peripatetic contexts, with particular focus on whether Augustine misrepresents his predecessors’ doctrines. Based upon a critical examination of recent research and a systematic analysis of Augustine's position in various phases of his writing, this article argues for a dynamic scheme of the psychotherapy of passions in Augustine's late thought, in which he deliberately deviates from philosophical traditions by adopting new criteria to re-evaluate the quality of emotions from the perspective of theological anthropology. This dynamic theological vantage point contributes to Augustine's insight into passions as well as his new use of the philosophical terms in refuting the Stoic pride.