This book investigates the conceptualization of regret (metameleia) within the moral psychology of Plato, Aristotle, and the Stoics to determine its function in ethical development. James Warren, a scholar of ancient philosophy, examines how these thinkers positioned regret as a specific emotional state distinct from both total virtue and total vice. By analyzing primary texts, the author argues that these philosophers viewed regret as a retrospective pain triggered by the realization of a past error, serving as a critical indicator of an agent's progress toward or away from moral excellence.

Scholars and students of classical philosophy frequently note the rigorous academic density of the prose and the precision of Warren's textual analysis. Experts highlight this work as a significant contribution to the study of ancient moral psychology, particularly for its clear articulation of how regret functions within the broader context of ethical agency.