This is an introduction to the most important theological work of the Middle Ages. In the intellectual tradition of the Christian faith, few thinkers have had a more profound effect upon both the nature of theology and the materials with which it deals than Thomas Aquinas. A knowledge, therefore, of his major work, the "Summa Theologiae", is necessary for the student of theology, let alone any who are concerned with the Western intellectual tradition, so pervasive is Aquinas' thought to the fabric of Western thought. This, together with the immensity, length, and difficulty of the Summa, make a Reader's Guide valuable, even crucial, to a student's first exposure to this work. To address the needs of undergraduates who attempt a reading of this work, Stephen Loughlin presents the basic principles that underlie the "Summa Theologiae" both as a whole and with respect to its three parts, and the varying treatises found within them. "Continuum Reader's Guides" are clear, concise and accessible introductions to key texts in literature and philosophy. Each book explores the themes, context, criticism and influence of key works, providing a practical introduction to close reading, guiding students towards a thorough understanding of the text. They provide an essential, up-to-date resource, ideal for undergraduate students.