7 The question of human procreation, like every other question which touches human life, involves more than the limited aspects specific to such disciplines as biology, psychology, demography or sociology. It is the whole man and the whole mission to which he is called that must be considered: both its natural, earthly aspects and its supernatural, eternal aspects. And since in the attempt to justify artificial methods of birth control many appeal to the demands of married love or of responsible parenthood, these two important realities of married life must be accurately defined and analyzed. This is what We mean to do, with special reference to what the Second Vatican Council taught with the highest authority in its Pastoral Constitution on the Church in the World of Today.
Source: Humanae Vitae (Vatican.va)