30 And now as We come to the end of this encyclical letter, We turn Our mind to you, reverently and lovingly, beloved and venerable brothers in the episcopate, with whom We share more closely the care of the spiritual good of the People of God. For We invite all of you, We implore you, to give a lead to your priests who assist you in the sacred ministry, and to the faithful of your dioceses, and to devote yourselves with all zeal and without delay to safeguarding the holiness of marriage, in order to guide married life to its full human and Christian perfection. Consider this mission as one of your most urgent responsibilities at the present time. As you well know, it calls for concerted pastoral action in every field of human diligence, economic, cultural and social. If simultaneous progress is made in these various fields, then the intimate life of parents and children in the family will be rendered not only more tolerable, but easier and more joyful. And life together in human society will be enriched with fraternal charity and made more stable with true peace when God's design which He conceived for the world is faithfully followed.
Source: Humanae Vitae (Vatican.va)