This collection of essays is a compilation of the thought and work of W. Norris Clarke, S.J., a philosopher inspired by the Thomistic tradition, who in 45 years of teaching and writing has delved into many of the central problems of perennial philosophy and made a significant contribution to the ongoing history of American Thomism. The essays presented here reflect an internal unity-each essay deliberately building on the positions put forth in the preceding ones-as they progress systematically through the themes of metaphysics and philosophy of God. Clarke begins with an overall survey of what in Aquinas's metaphysics is most relevant for today, and then suggests the most fruitful starting point for a contemporary presentation of such a metaphysics. The next five essays discuss key positions in metaphysics and are followed by two essays on the philosophy of God. The final essay illuminates key themes in Clarke's most recent work on the human person. Clarke's examination of topics in all these areas is especially concerned with the notions of action and participation in existence as being central to the metaphysical study of reality. This then leads to a close study of the often misunderstood Thomistic doctrine of analogy and how it functions in the construction of a viable philosophy of God. The overall spirit that permeates the volume is Clarke's firm conviction that the philosophical thought of St. Thomas Aquinas is an inexhaustibly rich and profound resource, and his purpose is to share this conviction with contemporary philosophers. In so doing Clarke both reflects and triggers significant new directions in contemporary Thomistic thought.