This is a brief and accessible introduction to the thought of the great Franciscan theologian St. Bonaventure (c. 1217-74). Cullen focuses on the long-debated relation between philosophy and theology in the work of this important but neglected thinker, revelaing Bonaventure as a great synthesizer. Cullen's exposition also shows in a new and more nuanced way Bonaventure's debt to Augustine, while making clear how he was influenced by Aristotle. The book is organized according to the categories of Bonaventure's own classic text. De reductione artium ad theologiam. Part I is devoted to the definition of Christian Wisdom. In Part II, "The Light of Philosophical Knowledge," individual chapters are devoted to Bonaventure's physics, metaphysics, and moral philosophy. Part III, "The Light of Theological Knowledge," includes chapters on the Trinity, Creation, Sin, the Incarnation, Grace, the Sacraments, and the Last Things.