[1] Subtitled On the Regulation of Birth, it re-affirmed the teaching of the Catholic Church regarding married love, responsible parenthood, and the rejection of artificial contraception.

[3] In this encyclical Paul VI reaffirmed the Catholic Church's view of marriage and marital relations and a continued condemnation of "artificial" birth control.

For this reason, Paul VI teaches in the first sentence of Humanae vitae, that the "transmission of human life is a most serious role in which married people collaborate freely and responsibly with God the Creator.

[9] The question of human procreation with God, exceeds in the view of Paul VI specific disciplines such as biology, psychology, demography or sociology.

It then goes on to observe that circumstances often dictate that married couples should limit the number of children, and that the sexual act between husband and wife is still worthy even if it can be foreseen not to result in procreation.

"[13] The encyclical also points out that the Roman Catholic Church cannot "declare lawful what is in fact unlawful", because she is concerned with "safeguarding the holiness of marriage, in order to guide married life to its full human and Christian perfection.

Paul VI predicted that future progress in social cultural and economic spheres would make marital and family life more joyful, provided God's design for the world was faithfully followed.

"[18] There had been a long-standing general Christian prohibition on contraception and abortion, with such Church Fathers as Clement of Alexandria and Saint Augustine condemning the practices.

Casti connubii is against contraception and regarding natural family planning allowed married couples to use their nuptial rights "in the proper manner" when because of either time or defects, new life could not be brought forth.

As Vatican Council II was concluding, Pope Paul VI enlarged it to fifty-eight members, including married couples, laywomen, theologians and bishops.

The "duty of responsible parenthood" was affirmed, but the determination of licit and illicit forms of regulating birth was reserved to Pope Paul VI.

"[23] After two more years of study and consultation, the pope issued Humanae vitae, which removed any doubt that the Church views hormonal anti-ovulants as contraceptive.

[25][26] In his role as Theologian of the Pontifical Household, Mario Luigi Ciappi advised Pope Paul VI during the drafting of Humanae vitae.

Gilfredo Marengo, a professor of theological anthropology at the Pontifical John Paul II Institute for Studies on Marriage and Family, launched a research project he called "a work of historical-critical investigation without any aim other than reconstructing as well as possible the whole process of composing the encyclical".

Hence to use this divine gift while depriving it, even if only partially, of its meaning and purpose, is equally repugnant to the nature of man and of woman, and is consequently in opposition to the plan of God and His holy will.

But to experience the gift of married love while respecting the laws of conception is to acknowledge that one is not the master of the sources of life but rather the minister of the design established by the Creator.

[33]Cardinal Leo Joseph Suenens, a moderator of the ecumenical council, questioned, "whether moral theology took sufficient account of scientific progress, which can help determine, what is according to nature.

"[34] In an interview in Informations Catholiques Internationales on 15 May 1969, he criticized the Pope's decision again as frustrating the collegiality defined by the council,[35] calling it a non-collegial or even an anti-collegial act.

Charles Curran, then Catholic University of America, issued a statement stating, "spouses may responsibly decide according to their conscience that artificial contraception in some circumstances is permissible and indeed necessary to preserve and foster the value and sacredness of marriage.

In Colombia, Cardinal Aníbal Muñoz Duque declared, "if American conditionality undermines Papal teachings, we prefer not to receive one cent".

[46] The Senate of Bolivia passed a resolution, stating that Humanae vitae can be discussed in its implications on individual consciences, but is of greatest significance because it defends the rights of developing nations to determine their own population policies.

[47] However, against eighteen insubordinate priests, professors of theology at Pontifical Catholic University of Chile, and the ensuing conspiracy of silence practiced by the Chilean Episcopate, which had to be censured by the Nuncio in Santiago at the behest of Cardinal Gabriel-Marie Garrone, prefect of the Congregation for Catholic Education, triggering eventually a media conflict with El Diario Ilustrado [es], Plinio Corrêa de Oliveira expressed his affliction with the lamentations of Jeremiah: "O ye all that pass through the way…" (Lamentations 1:12, King James Bible).

Acknowledging the controversy, Paul VI in a letter to the Congress of German Catholics (30 August 1968), stated: "May the lively debate aroused by our encyclical lead to a better knowledge of God's will.

[54] Increasingly convinced, that "the smoke of Satan entered the temple of God from some fissure",[55] Paul VI reaffirmed, on 23 June 1978, weeks before his death, in an address to the College of Cardinals, his Humanae vitae: "following the confirmations of serious science", and which sought to affirm the principle of respect for the laws of nature and of "a conscious and ethically responsible paternity".

[56] In his last letter to Pope Paul VI, Christian mystic and canonized saint Padre Pio called Humanae vitae "clear and decisive words".

"[65] After he became pope in 1978, John Paul II continued on the Catholic Theology of the Body of his predecessors with a series of lectures, entitled Theology of the Body, in which he talked about an "original unity between man and women",[66] purity of heart (on the Sermon on the Mount), marriage and celibacy and reflections on Humanae vitae, focusing largely on responsible parenthood and marital chastity.

[67] In 1981, the Pope's Apostolic exhortation, Familiaris consortio, restated the Church's opposition to artificial birth control stated previously in Humanae vitae.

John Paul quoted Humanae vitae as a compassionate encyclical, "Christ has come not to judge the world but to save it, and while he was uncompromisingly stern towards sin, he was patient and rich in mercy towards sinners".

On 12 May 2008, Benedict XVI accepted an invitation to talk to participants in the International Congress organized by the Pontifical Lateran University on the 40th anniversary of Humanae vitae.

But his genius was prophetic, he had the courage to take a stand against the majority, to defend moral discipline, to exercise a cultural restraint, to oppose present and future neo-Malthusianism.