(11) "(T)he Church, calling men back to the observance of the norms of the natural law, as interpreted by its constant doctrine, teaches that each and every marriage act (quilibet matrimonii usus) must remain open to the transmission of life.
(12) "That teaching, often set forth by the Magisterium, is founded upon the inseparable connection, willed by God and unable to be broken by man on his own initiative, between the two meanings of the conjugal act: the unitive meaning and the procreative meaning. Indeed, by its intimate structure, the conjugal act, while most closely uniting husband and wife, capacitates them for the generation of new lives, according to laws inscribed in the very being of man and of woman. By safeguarding both these essential aspects, the unitive and the procreative, the conjugal act preserves in its fullness the sense of the true mutual love and its ordination towards man's most high calling to parenthood. We believe that the men of our day are particualrly capable of seizing the deeply reasonable and human character of this fundamental principle."
The Church’s view of “conjugal love”
(9) “This love is first of all fully human, that is to say, of the senses and of the spirit at the same time…intended to endure and to grow by means of the joys and sorrows of daily life, in such a way that husband and wife become one heart and one soul, and together attain their human perfection.
“This love is total, that is to say, it is a very special form of personal friendship, in which husband and wife generously share everything, without undue reservations or selfish calculations.
“Again, this love is faithful and exclusive until death…, a fidelity which can sometimes be difficult, but is always possible, always noble and meritorious, as no one can deny.
“Finally this love is fruitful for it is not exhausted by the communion between husband and wife, but is destined to continue, raising up new lives.”