  Without exception, every word of philosophy Bonaventure ever wrote is contained in works explicitly religious—in sermons, works of spiritual direction, and theology. He never wrote the kind of introductions to the principles of metaphysics and natural philosophy that Thomas Aquinas composed in his On Being and Essence (De ente et essentia) and On the Principles of Nature (De principiis naturae), nor did he comment on Aristotle’s works. Commentators writing during the twentieth century neo-thomistic revival compared Bonaventure with three other thinkers: Aristotle, Augustine, and Aquinas. P. Mandonnet thought he had no philosophy of his own, but was an Augustinian theologian, pure and simple, all of whose conclusions depend on faith. E. Gilson thought Bonaventure developed an Augustinian philosophy within his theology: “with St. Bonaventure the mystical synthesis of mediaeval Augustinianism was fully formed, just as that of Christian Aristotelianism was fully formed with St. Thomas.” F. Van Steenberghen thought his philosophy a failed Aristotelianism separate from but at the service of his Augustinian  theology.[10]  None of these interpretations quite captures Bonaventure’s relation to these three philosophers or his own approach to the relations among reason, faith, and theology, because they implicitly employed a Thomistic model for being an Aristotelian, with the result that Bonaventure’s failures derive from his not being the kind of Aristotelian Thomas Aquinas was.