Sixty-five years ago on the Solemnity of Sts. Peter and Paul, Joseph Aloisius Ratzinger was ordained a Roman Catholic priest, following a call from the Lord that would set this brilliant, shy scholar on the path to the chair of Peter.

On June 28, in his first public address since his resignation in 2013, Pope Emeritus Benedict XVI celebrated the day he received holy orders. During a joint appearance with Pope Francis at the Vatican’s Clementine Hall, Benedict offered a brief meditation on the vocation that still gives him joy.

Efkaristomen — a Greek word inscribed on the memorial card for his first Mass by a fellow priest — was the same word he chose to explain the sense of gratitude that transformed his priestly life, from his ordination to his cloistered existence within the Vatican.

Efkaristomen, he said, points to both “the dimensions of human thanksgiving” and the deeper truth of the words that appear in the liturgy and in Scripture: Gratias agens benedixit fregit deditque — “Having given thanks, he broke it and gave it.”

Jesus transformed into thanksgiving “the cross, suffering and all of the evil in the world.” Today, we still receive “the Bread of true life, which overcomes the world, thanks to the strength of his love,” he explained.

The brief meditation offered a window into the soul of a gifted preacher and teacher. Throughout his papacy, and during the years preceding it, he took every opportunity to shed light on the mysteries and truths of the faith in ways that brought the Gospels to life and helped his audience to see things as they were, not as we wished them to be.

His rare appearance with Pope Francis also underscored a new moment in the history of the papacy. While Pope Francis is visibly engaged in the work of the Vicar of Christ, Pope Emeritus Benedict has taken up a starkly contemplative existence within the Vatican.

In 2013, Benedict roiled the Church and the world when he announced his resignation. In the tumultuous aftermath of the news, and the preparations for a conclave to elect a new pope, some theologians feared the presence of “two popes” — one active and the other retired — would damage respect for the primacy of Peter.

“I never forget that speech he made to us cardinals on Feb. 28: ‘Among you, I’m sure, is my successor. I promise obedience,’” recalled Pope Francis during his June 26 flight home from Armenia. “And he has done it.”

Pope Francis expressed gratitude for Benedict’s landmark decision to create a new “institution” of pope emeritus and for his unquestioned obedience to the primacy of the Vicar of Christ.

This May, Archbishop Georg Gänswein, Benedict’s personal secretary and prefect of the pontifical household, shared his own insights into this new chapter in the history of the papacy.

According to Archbishop Gänswein, the papal office “remains the foundation of the Catholic Church; and yet it is a foundation that Benedict XVI has profoundly and lastingly transformed during his exceptional pontificate,” said Archbishop Gänswein during an address at a May 20 event that introduced a new book on Benedict’s pontificate at the Pontifical Gregorian University in Rome.

He added that, in the three years since Benedict’s resignation, the pope emeritus “has built a personal office with a collegial and synodal dimension, almost a communal ministry, as if he had wanted to reiterate once again the invitation contained in the motto that the then-Joseph Ratzinger had as archbishop of Munich and Freising and naturally maintained as bishop of Rome: cooperatores veritatis, which means ‘co-workers of the truth.’”

Celebrated for his humble, courageous witness to truth, this man of the Church is an appropriate messenger for this organic development in Petrine ministry.

In 2005, as the Church mourned the death of Pope St. John Paul II and the College of Cardinals prepared to elect his successor, it was then-Cardinal Ratzinger who warned of a looming “dictatorship of relativism,” and so raised the stakes for the papal election.

After his election, Pope Benedict echoed the themes that defined John Paul’s papacy and made the Polish pontiff and German prefect of the Congregation for the Doctrine of the Faith “co-workers of the truth.”

But while John Paul sought to liberate Eastern Europe from the yoke of Soviet rule, Benedict addressed the self-inflicted wounds that marked the West’s repudiation of its Christian roots.

“Amid the major upheavals of our day, is there a European identity that has a future and to which we can commit wholeheartedly?” he asked, in his 2006 book Without Roots, excerpted in First Things magazine.

A decade later, that question is more relevant than ever, as the Continent struggles to come to grips with the migrant crisis and Britain’s vote to withdraw from the European Union.

Likewise, as the U.S. Supreme Court upholds the redefinition of marriage and overturns restrictions on abortion businesses in Texas, it is worth pondering Benedict’s pointed warning about the wages of secularism.

“Fundamental rights are neither created by the lawmaker nor granted to the citizen. The value of human dignity, which takes precedence over all political action and all political decision-making, refers to the Creator: Only he can establish values that are grounded in the essence of humankind and are inviolable,” he wrote in Without Roots.

This trenchant critique of secularism has made Benedict unpopular in some circles. But his detractors missed the larger message of his papacy.

“Being Christian is not the result of an ethical choice or a lofty idea, but the encounter with an event, a Person, which gives life a new horizon and a decisive direction,” wrote Benedict in his first papal encyclical, Deus Caritas Est (God Is Love). “Since God has first loved us (1 John 4:10), love is now no longer a mere ‘command’; it is the response to the gift of love with which God draws near to us.”

Today, we, too, join in celebrating the 65th anniversary of Benedict’s ordination. And as we thank God for his priestly ministry, let us share his joy that Jesus has truly transformed into thanksgiving “the cross, suffering and all of the evil in the world.”