Two basic sources for Catholic Theology are the Sacred Scripture and the documents of the Magisterium. In the same way as Catholic theologians and exegetes must know how to distinguish among the various literary forms in the Bible and how to interpret scriptural texts, they must also know how to determine the relative degree of authority exercised in the various documents issued by the popes or ecumenical councils and how to apply the principles of hermeneutics in interpreting them. Hence this book offers guidelines that will help those interested in Catholic theology to make sound judgments about the authority and meaning of the documents in which the Church has expressed its faith over the centuries. The book is indispensable in the context of contemporary discussions on delicate issues of Christian faith and praxis. The task of the interpreter is one of creative fidelity, requiring a delicate balance between being faithful to the original meaning of the text and creative in finding the concepts and terms that make it meaningful in our times.