No member of the faithful could possibly deny that the Church is competent in her magisterium to interpret the natural moral law. It is in fact indisputable, as Our predecessors have many times declared, that Jesus Christ, when He communicated His divine power to Peter and the other Apostles and sent them to teach all nations His commandments, constituted them as the authentic guardians and interpreters of the whole moral law, not only, that is, of the law of the Gospel but also of the natural law. For the natural law, too, declares the will of God, and its faithful observance is necessary for men’s eternal salvation.
In carrying out this mandate, the Church has always issued appropriate documents on the nature of marriage, the correct use of conjugal rights, and the duties of spouses. These documents have been more copious in recent times.
The consciousness of the same responsibility induced Us to confirm and expand the commission set up by Our predecessor Pope John XXIII, of happy memory, in March, 1963. This commission included married couples as well as many experts in the various fields pertinent to these questions. Its task was to examine views and opinions concerning married life, and especially on the correct regulation of births; and it was also to provide the teaching authority of the Church with such evidence as would enable it to give an apt reply in this matter, which not only the faithful but also the rest of the world were waiting for.
