The papacy is clearly the greatest difficulty facing ecumenical dialogue today, and particularly the dialogue between Catholicism and Orthodoxy. Yet there is a doorway of hope. In his encyclical, Ut unum sint, John Paul II expressed a desire for common reflection on the exercise of papal primacy. In You Are Peter the great Orthodox theologian Olivier Clement brilliantly responds to this request. He emphasizes the history and experience of the undivided...