INTRODUCTION
The Second Vatican Council, with its Dogmatic Constitution Lumen gentium, and its Decrees on Ecumenism (Unitatis redintegratio) and the Oriental Churches (Orientalium Ecclesiarum), has contributed in a decisive way to the renewal of Catholic ecclesiology. The Supreme Pontiffs have also contributed to this renewal by offering their own insights and orientations for praxis: Paul VI in his Encyclical Letter Ecclesiam suam (1964) and John Paul II in his Encyclical Letter Ut unum sint (1995).