In his inaugural encyclical Ecclesiam suam (section below), the pope called Mary the ideal of Christian perfection. He regards "devotion to the Mother of God as of paramount importance in living the life of the Gospel." Encyclicals Paul VI authored seven encyclicals. Ecclesiam suam Ecclesiam suam was given at St. Peter's, Rome, on the Feast of the Transfiguration, 6 August 1964, the second year of his Pontificate. It is considered an important document, identifying the Catholic Church with the Body of Christ. A later Council document Lumen Gentium stated that the church subsists in the Body of Christ, raising questions as to the difference between "is" and "subsists in". Paul VI appealed to "all people of good will" and discussed necessary dialogues within the church and between the churches and with atheism. Mense maio The encyclical Mense maio (from 29 April 1965) focused on the Virgin Mary, to whom traditionally the month of May is dedicated as the Mother of God. Paul VI writes that Mary is rightly to be regarded as the way by which people are led to Christ. Therefore, the person who encounters Mary cannot help but encounter Christ. Mysterium fidei On 3 September 1965, Paul VI issued Mysterium fidei, on the mystery of the faith. He opposed relativistic notions which would have given the Eucharist a symbolic character only. The church, according to Paul VI, has no reason to give up the deposit of faith in such a vital matter. Christi Matri Populorum progressio Populorum progressio, released on 26 March 1967, dealt with the topic of "the development of peoples" and that the economy of the world should serve mankind and not just the few. It touches on a variety of traditional principles of Catholic social teaching: the right to a just wage; the right to security of employment; the right to fair and reasonable working conditions; the right to join a union and strike as a last resort; and the universal destination of resources and goods. In addition, Populorum progressio opines that real peace in the world is conditional on justice. He repeats his demands expressed in Bombay in 1964 for a large-scale World Development Organization, as a matter of international justice and peace. He rejected notions to instigate revolution and force in changing economic conditions. Sacerdotalis caelibatus Sacerdotalis caelibatus (Latin for "Of the celibate priesthood"), promulgated on 24 June 1967, defends the Catholic Church's