Evangelii Nuntiandi §65

65. It was precisely in this sense that at the end of the last Synod we spoke clear words full of paternal affection, insisting on the role of Peter's Successor as a visible, living and dynamic principle of the unity between the Churches and thus of the universality of the one Church.[93] We also insisted on the grave responsibility incumbent upon us, but which we share with our Brothers in the Episcopate, of preserving unaltered the content of the Catholic faith which the Lord entrusted to the apostles. While being translated into all expressions, this content must be neither impaired nor mutilated. While being clothed with the outward forms proper to each people, and made explicit by theological expression which takes account of differing cultural, social and even racial milieu, it must remain the content of the Catholic faith just exactly as the ecclesial magisterium has received it and transmits it.

93. Paul VI, Address for the closing of the Third General Assembly of the Synod of Bishops (26 October 1974): AAS 66 (1974), p. 636.