The Middle Ages witnessed tremendous strides in the development of Western philosophical thought, culminating in the arrival of Aristotelianism, the installation of Scholasticism, and the great triumph of Thomism. Conventional wisdom on the topic, however, often elides an essential element of the Medieval philosophical project: namely, in Étienne Gilson?s powerful phrasing, that it was ?crowned by mysticism, [as] numberless living souls were on the watch, seeking an order of ideas and things capable of satisfying them.? Among these souls, none stands higher than the Seraphic Doctor, Saint Bonaventure. In this masterful survey of the spirit and substance of Bonaventure?s philosophical contribution, Gilson ranges from the existence and essence of God and his will and providence, to creation, the angels, and the intellectual and moral life of man, with special attention to the interplay of grace and nature in the pursuit of beatitude. At the heart of The Philosophy of Saint Bonaventure is the affective life of the Middle Ages, as Gilson demonstrates the abiding unity of mind and heart in the Christian intellectual life, where the desire both to know and to love is fulfilled.