If Saint Thomas Aquinas was a great theologian, it is in no small part because he was a great philosopher. And he was a great philosopher because he was a great metaphysician. In the twentieth century, metaphysics was not much in vogue, among either theologians or even philosophers; but now it is making a comeback, and once the contours of Thomas's metaphysical vision are glimpsed, it looks like anything but a museum piece. It only needs some dusting off. Many are studying Thomas now for the answers that he might be able to give to current questions, but he is perhaps even more interesting...