The Summa Illuminated: A Guide to St. Thomas Aquinas's Masterpiece

“This book is the ordinary reader’s clearest introduction to the Summa Theologica. It illuminates the obscure and enlivens the dispassionate arguments of St. Thomas Aquinas. Everyone should be reading St. Thomas, and I can’t imagine a better guide than Fr. Cajetan Cuddy.”—Scott Hahn

The Summa Illuminated offers a clear and concise introduction to one of the most influential theological masterpieces in history: the Summa Theologica by St. Thomas Aquinas (c. 1225–1274). As interest in Aquinas’s teachings continues to grow, many are especially drawn to his Summa Theologica—yet navigating its profound depth and intricate complexity can feel overwhelming without proper guidance. 

In The Summa Illuminated, Fr. Cajetan Cuddy, OP, premier expert on both the Summa and the philosophy and theology of St. Thomas Aquinas, provides readers with a concise and approachable overview. This book serves as a guided tour of the Summa, carefully laying out its structure, explaining its key concepts, and clarifying Aquinas’s overarching purpose. Following the structure of the Summa itself, this book captures the significance of each part and illustrates how they form a unified whole while explaining the terminology and principles that Aquinas presupposed his audience to possess.

Fr. Cuddy guides the reader through the significant themes of the Summa’s three parts: 

• Part I: God and Creation
• Part II: The Human Person’s Movement to God—Law, Grace, and Virtues
• Part III: Jesus Christ and the Sacraments

The Summa Illuminated equips readers with the essential knowledge to confidently engage with Aquinas’s great work. By the end, readers will have a firm grasp of the most important ideas in the greatest theological text of the Catholic intellectual tradition.