1. God has entrusted spouses with the extremely important mission of transmitting human life. In fulfilling this mission spouses freely and deliberately render a service to God, the Creator. This service has always been a source of great joy, although the joys are, at times, accompanied by not a few difficulties and sufferings.
Fulfilling this mission has always raised some difficult questionS for the consciences of married couples. Furthermore, in recent times, the evolution of human society has brought with it changes that raise new questions. The Church can.not ignore these questions, for they concern matters intimately connected with human life and happiness.
2. The various changes that have taken place [in modern times] are truly of great importance. In the first place, there has been a rapid increase in population, an increase that causes many to fear that the population of the earth will grow faster than its available life sustaining resources. This [disparity] could result in even greater hardships for many families and for many developing nations. Public authorities may easily be tempted to fight the danger by rather severe methods. Moreover, contemporary conditions of work and housing, as well as increased expenses involved in providing for, raising, and educating children, often make it burdensome to support a large family adequately.
It must also be noted that there have been changes in how we view the person of woman and how we view her role in society; indeed there have even been changes in the value we place on conjugal love and on how we understand the meaning of acts of sexual intercourse in light of this love.
Finally, and above all, it must be noted that because Man has made such remarkable progress in controlling the forces of nature and in rationally organizing them, he also strives to extend this control to the whole of his life: that is, to his body, to the powers of his mind, to his social life, and even to the laws that regulate the propagation of life.
3. This state of affairs gives rise to new questions. [Some ask:] Given the conditions of life today and given the importance of marital intercourse for marital harmony and fidelity, is it not appropriate to reconsider the moral norms that have obtained up to now? Is not a reconsideration especially appropriate if it is believed that these norms cannot be observed without serious ~ sacrifices, sometimes heroic sacrifices?
Or is it not possible to apply the so-called principle of totality to this problem? Would it not be possible to use this principle to justify using one's reason to reduce one's fertility? Would not an act that causes sterility become a licit and prudent way to limit one's family size? That is, would it not clearly be right to consider the goal of having children to pertain more to the whole of married life than to each and every act of sexual intercourse? And, again, given the fact that moderns have an increased sense of their responsibilities, [they ask] whether it is not right for them to entrust the mission of transmitting life more to their reason and will than to the biological rhythms of their bodies?
4. Certainly questions of this kind require that the Magisterium of the Church give new and deeper consideration to the principles of the moral teaching concerning marriage, a teaching that is rooted in natural law, illuminated and made richer by divine revelation.
Let no one of the faithful deny that the Magisterium of the Church is competent to interpret the natural moral law. For it is indisputable — as Our predecessors have often declared 1 — that when Jesus Christ imparted His divine authority to Peter and the other apostles and sent them to all nations to teach His Commandments, 2 He established those very men as authentic guardians and interpreters of the whole moral law, that is, not only of the law of the Gospel, but also of natural law. For natural law [as well as revealed law] declares the will of God; [thus] compliance with natural law is necessary for eternal salvation. 3
Moreover, the Church has always been faithful in fulfilling this command. In recent times, she has more amply provided an integrated teaching on the nature of marriage, on the moral use of conjugal rights, and on the duties of the spouses. 4
5. Conscious of Our responsibility in this regard, We approved and enlarged the commission established by Our venerable predecessor John XXIII in March of 1963. In addition to many experts in the relevant disciplines, the commission also included married couples. The commission was to consider opinions and views concerning married life and, in particular, [it was to reflect upon] the legitimate means of controlling family size. It was to report the results in due time to the Magisterium so that it could provide a fitting response to the faithful and to people worldwide who are awaiting an answer. 5
The investigation of the experts and the opinions and advice from Our confreres in the Episcopate — some spontaneously offered and some solicited by Us — enabled Us to consider very thoroughly all aspects of this complex subject. For which reason We offer our most sincere thanks to all.
6. We could not, however, consider the conclusions of the commission in themselves as carrying the force of a certain and definite judgment; nor could their judgment relieve Us of Our duty of deciding a question of such great importance through Our own consideration. There were several reasons why this was necessary. First, there was no full concession within the commission concerning what moral norms ought to be proposed. And even more importantly, certain methods and criteria were used in answering the question that departed from the firm and constant teaching of the Magisterium on what is moral within marriage.
We have carefully evaluated the findings sent to Us and most thoroughly considered this matter. Now, after assiduous prayer, We think it right, through the power given to Us by Christ, to give an answer to these weighty questions.