"To do theology - as the Magisterium understands theology - it is not sufficient merely to calculate how much religion can reasonably be expected of man and to utilize bits and pieces of the Christian tradition accordingly. Theology is born when the arbitrary judgment of reason encounters a limit, in that we discover something which we have not excogitated ourselves but which has been revealed to us. For this reason, not every religious theory has the right to label itself as Christian or Catholic theology simply because it wished to do so; whoever would lay claim to this title is obliged to accept as meaningful the prior given which goes along with it.

"In today's situation, the dialogue concerning theology and the clarification of its methods, its mission and its limits have become urgent. The individual sections of this book were occasioned by the challenges of this dialogue. They do not form a systematic treatise on theology, a project which my professional obligations unfortunately do not permit me to undertake. Rather, the pieces assembled here represent so many preliminary approaches to the subject from diverse points of view. I hope that precisely in their openness to further development these first efforts can help the nature of the theologian's work in today's circumstances to be better understood as well as to sustain it in its essential task: to serve the knowledge of the truth of revelation and, in so doing, unity in the Church."
- Joseph Cardinal Ratzinger
From the Foreword