Gaudet Mater Ecclesia (Latin for "Mother Church Rejoices") is the title of Pope John XXIII's opening speech of the Second Vatican Council.
In the speech, addressed to "a vast assembly" of over 2000 bishops,[1] he rejected the thoughts of "prophets of doom who are always forecasting disaster" in the world and in the future of the Church.
[2] Gaudet Mater Ecclesia stated the purpose of the Second Vatican Council to be defending and presenting the sacred deposit of Christian doctrine: The greatest concern of the Ecumenical Council is this, that the sacred deposit of Christian doctrine should be more effectively defended and presented.
[4] In its relationship with the modern world, John declared that the Church "meets today’s needs by explaining the validity of her doctrine more fully rather than by condemning" the alternatives.
[1] The Feast of the Maternity of the Blessed Virgin Mary was celebrated on 11 October each year prior to the Council.