I believe that the Traditional Rites of East and West contain within themselves so many elements of Apostolic origin that it is impossible to separate these from the elements added by post-Apostolic ecclesiastical tradition.
I believe no man here on earth (Pastor Aeternus, IV, 6) can rightfully determine the complete abrogation, full substitution, or substantial derogation of any received Traditional Rite, of East and West, which contains inextricable Apostolic elements.
I believe Ecclesiastical History continuously proves that the rights of the liturgical rites "established by long and immemorial prescription" have always been respected by the Holy Roman Church, even in ages of great liturgical crises and heresies (Quo Primum; Quod a Nobis).
Glory be to the Father, and to the Son, and to the Holy Ghost,
as it was in the beginning, is now, and ever shall be, world without end.