Acting on Principles, the product of over thirty years of teaching, gives a comprehensive overview of the Moral Theology of St. Thomas Aquinas, placing it in dialogue with contemporary ethical theory and developments in Catholic theology since the Second Vatican Council. Suitable for students of ethics and moral theology, and general readers seeking Christian guidance in the formation of conscience and moral decision making, it presents the classical Catholic ethical tradition in a clear and lively style.

Recent studies of medieval preaching have tended to focus on sermon texts. This is the first scholarly study in English of preaching and its social context in thirteenth-century Italy. Augustine Thompson O.P., both an academic and a preacher, reconstructs the "Great Devotion" of 1233 and analyzes its devotional, social, political, and legal elements. He shows how the preachers of this revival crafted an image of divine authority that supported their intervention in factional disputes and facilitated their arbitration in social and political conflicts. They exploited forms from revived Roman Law and developing city statutes in order to create flexible procedures for mediation, and ultimately were able to revise communal ordinances to enshrine their message of social harmony. This is a work of original scholarship, carefully researched and lucidly written, which is a valuable contribution to our understanding of religion and politics in the middle ages.