In his Encyclical Letter Humanae Vitae of July 25, 1968 Paul VI observed:
The
sexual activity, in which husband and wife are intimately and chastely united
with one another, through which human life is transmitted, is, as the recent
Council recalled, "noble and worthy.'' It does not, moreover, cease to be
legitimate even when, for reasons independent of their will, it is foreseen to
be infertile. For its natural adaptation to the expression and strengthening of
the union of husband and wife is not thereby suppressed. The fact is, as
experience shows, that new life is not the result of each and every act of
sexual intercourse. God has wisely ordered laws of nature and the incidence of
fertility in such a way that successive births are already naturally spaced
through the inherent operation of these laws. The Church, nevertheless, in
urging men to the observance of the precepts of the natural law, which it
interprets by its constant doctrine, teaches that each and every marital act
must of necessity retain its intrinsic relationship to the procreation of human
life.
This
particular doctrine, often expounded by the magisterium of the Church, is based
on the inseparable connection, established by God, which man on his own initiative
may not break, between the unitive significance and the procreative
significance which are both inherent to the marriage act. The reason is that
the fundamental nature of the marriage act, while uniting husband and wife in
the closest intimacy, also renders them capable of generating new life—and this
as a result of laws written into the actual nature of man and of woman. And if
each of these essential qualities, the unitive and the procreative, is
preserved, the use of marriage fully retains its sense of true mutual love and
its ordination to the supreme responsibility of parenthood to which man is
called. We believe that our contemporaries are particularly capable of seeing
that this teaching is in harmony with human reason.
It is encouraging that Catholic scholars continue to promote Catholic truth in our time of increasing secualrization and devaluing of the dignity of the human body....
