Among the great philosophers of the Middle Ages Aquinas is unique in pursuing two apparently disparate projects. On the one hand he developed a philosophical understanding of Christian doctrine in a fully integrated system encompassing all natural and supernatural reality. On the other hand, he was convinced that Aristotle`s philosophy afforded the best available philosophical component of such a system. In a relatively brief career Aquinas developed these projects in great detail and with an astonishing degree of success. In this volume ten leading scholars introduce all the important aspects of Aquinas` thought, ranging from its historical background and dependence on Greek, Islamic, and Jewish philosophy and theology, through the metaphysics, epistemology and ethics, to the philosophical approach to Biblical commentary.