Although St Thomas Aquinas famously claimed that his Summa Theologiae was written for 'beginners', contemporary readers find it unusually difficult. Now, amid a surge of interest in virtue ethics, J. Budziszewski clarifies and analyzes the text's challenging arguments about the moral, intellectual, and spiritual virtues, with a spotlight on the virtue of justice. In what might be the first contemporary commentary on Aquinas' virtue ethics, he juxtaposes the original text with paraphrase and detailed discussion, guiding us through its complex arguments and classical rhetorical figures. Keeping an eye on contemporary philosophical issues, he contextualizes one of the greatest virtue theorists in history and brings Aquinas into the interdisciplinary debates of today. His brisk and clear style illuminates the most crucial of Aquinas' writings on moral character and guides us through the labyrinth of this difficult but pivotal work.