ROME – Addressing a group of liturgical experts on Thursday, Pope Francis said that after the teaching of the Second Vatican Council (1962-65) and a long path of experience, “We can affirm with certainty and magisterial authority that the liturgical reform is irreversible.”

The declaration came in a speech on Thursday to Italy’s “Center of Liturgical Action,” which sponsors an annual National Liturgical Week.

By “liturgical reform,” Pope Francis meant the changes in Catholic rituals and modes of worship which followed from Vatican II, the most immediately visible elements of which included Mass facing the congregation, the use of vernacular languages, and a stronger emphasis on the “full, conscious and active” participation of the people.

Although Pope Francis is often seen as having less interest in liturgical questions than some of his predecessors, this was a lengthy and carefully footnoted reflection, roughly 2,500 words in all.

He began by highlighting some of the cornerstones of the liturgical movement of the 20th century, a reminder that the ongoing reform is rooted in tradition, and was actually kick-started by two popes often seen as  “conservative”: Pius X, who created a commission for renewal in 1913, and Pius XII, with his encyclical Mediator Dei and changes to the liturgy of Holy Week.

According to Francis, these changes came to fruition with 1963’s Sacrosanctum Concilium, the Constitution on the Sacred Liturgy of the Second Vatican Council, the application of which is still ongoing, including overcoming “unfounded and superficial interpretations, partial revelations and practices that disfigure” [the liturgy].

Quoting Pope Paul VI, the Argentine pontiff added that this process is still ongoing in part because reforming the liturgical books is not enough to “renew the mentality.”

Also using the words of his predecessor, Francis called Catholics – priests and laity alike – to leave behind “disruptive ferments, which are equally pernicious in one sense and the other,” and to “apply integrally” the reform approved by the bishops who took part in the Council.

Battles over liturgical practice have been a chronic feature of Catholic life since Vatican II.

A desire to maintain the older Latin Mass, for instance, was a primary force prompting French Archbishop Marcel Lefebvre to lead a group of traditionalist Catholics into a break with Rome. During the 1990s, the church in the United States engaged in a decade-long debate over how to translate liturgical texts into English and other matters dubbed the “liturgy wars.”

There are even sometimes tensions inside the Vatican walls, where Francis and the Church’s top liturgical official, Cardinal Robert Sarah of Guinea, don’t always appear to see eye to eye –particularly on the value of the older Mass, celebrated in Latin and with the priest facing away from the congregation, now known as the Extraordinary form.

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After the Council, Francis told the Italian liturgists, the bishops wanted a liturgy that is “alive” for a Church “fully enlivened by the celebrated mysteries.”

He then gives three keys to a “living” liturgy: it’s centered in Christ, it involves the people, and works as a “school of Christian life.”

The liturgy is alive, he said, because of the “lively presence of Him who ‘dying has destroyed our death, and by rising, restored our life.” Without the presence of Christ, Francis insisted, there’s not liturgical vitality, just like there’s no human life without a beating heart.

Liturgy is also alive because it involves the entire people of the Church, he said, and by its nature it’s “popular” and not “clerical” because “it’s an action for the people, but also by the people.”

In her prayer, Francis said, the Church welcomes all those who have the heart to listen to the Gospel, without discarding anyone, not “rich or poor, young or old, healthy or sick, righteous or sinners.” Hence the liturgical assembly, he said, goes beyond every boundary of age, race, language and nationality.

Lastly, he said the liturgy must work as a school of life, “transforming one’s way of thinking and living, not just filling up a bag of ideas about God.”

The liturgy, Francis insisted, is not simply “a doctrine to understand or a rite to fulfill,” it’s a “source of life and light for our path of faith.

“There’s a big difference between hearing that God exists, and feeling that he loves us, just as we are, here and now,” he said. In the liturgical prayer, he said, Catholics experience a communion that finds its meaning not in an abstract thought but in an action made “by God and us, Christ and the Church.”

Towards the end of his remarks, Francis told those gathered that it must be remembered that the wealth of the Catholic Church’s prayer life goes beyond the Roman Rite.

“The harmony of the ritual traditions, from East to West, by the breath of the same Spirit gives voice to the one prayer for Christ, with Christ and in Christ, for the glory of the Father and for the salvation of the world,” he said.