With a few words in Latin, Pope Benedict XVI did what no pope has done in more than half a millennium, stunning Bishop Robert Gruss of Rapid City, along with the rest of the world, by announcing his resignation Monday and leaving the already troubled Catholic Church to replace the leader of its 1 billion followers by Easter.
"It was kind of shocking for me and I think for all Catholics," Gruss said Monday of the first pontifical resignation in 600 years.
Not even the pope's closest associates had advance word of the news, a bombshell that he dropped during a routine morning meeting of Vatican cardinals. And with no clear favorites to succeed him, another surprise likely awaits when the cardinals elect Benedict's successor next month.
"Without doubt this is a historic moment," said Cardinal Christoph Schoenborn, a protege and former theology student of Benedict's who is considered a papal contender. "Right now, 1.2 billion Catholics the world over are holding their breath."
Gruss called the resignation an act that "showed real humility in his own heart." He last saw Pope Benedict from a distance during the October canonization of the first Native American saint, St. Kateri Tekakawitha.
But he spoke face-to-face with Pope Benedict in March 2012 during an ad limina visit, when bishops go to the Vatican to report on the progress of their diocese. "He seemed very tired. We had two meetings with him, and at the first one he looked really, really tired and a bit sickly," he said. "Many who have seen him in the last months say he really doesn't look good physically."
Still, Gruss was surprised by the resignation, much as he was surprised eight years ago by the former Cardinal Joseph Ratzinger's election to the papacy.
"He was not certainly on the top list of candidates to become pope after the death of Pope John Paul II, and like a lot of people, I was kind of surprised by that. But the Holy Spirit moves in mysterious ways in the Catholic Church," he said. The academic theologian has become a pope with the "heart of a pastor," Gruss said.
The resignation allows for a fast-track conclave to elect a new pope, since the traditional nine days of mourning that would follow a pope's death doesn't have to be observed.
It also gives the 85-year-old Benedict great sway over the choice of his successor. Though he will not himself vote, he has hand-picked the bulk of the College of Cardinals — the princes of the church who will elect his successor — to guarantee his conservative legacy and ensure an orthodox future for the church.
Gruss would make no predictions on what part of the world a new pope might hail from, but he expects it to happen quickly in March.
The resignation may mean that age will become less of a factor when electing a new pope, since candidates may no longer feel compelled to stay for life.
"For the century to come, I think that none of Benedict's successors will feel morally obliged to remain until their death," said Paris Cardinal Andre Vingt-Trois.
Benedict said as recently as 2010 that a pontiff should resign if he got too old or infirm to do the job, but it was a tremendous surprise when he said in Latin that his "strength of mind and body" had diminished and that he couldn't carry on. He said he would resign effective 8 p.m. local time on Feb. 28.
"All the cardinals remained shocked and were looking at each other," said Monsignor Oscar Sanchez of Mexico, who was in the room at the time of the announcement.
As a top aide, Benedict watched from up close as Pope John Paul II suffered publicly from the Parkinson's disease that enfeebled him in the final years of his papacy. Clearly, Benedict wanted to avoid the same fate as his advancing age took its toll, though the Vatican insisted the announcement was not prompted by any specific malady.
The Vatican said Benedict would live in a congregation for cloistered nuns inside the Vatican, although he will be free to go in and out. Much of this is unchartered territory. The Vatican's chief spokesman, the Rev. Federico Lombardi, said he isn't even sure of Benedict's title — perhaps "pope emeritus."
Since becoming pope in 2005, Benedict has charted a very conservative course for the church, trying to reawaken Christianity in Europe where it had fallen by the wayside and return the church to its traditional roots, which he felt had been betrayed by a botched interpretation of the modernizing reforms of the Second Vatican Council.
His efforts though, were overshadowed by a worldwide clerical sex abuse scandal, communication gaffes that outraged Jews and Muslims alike and, more recently, a scandal over leaked documents by his own butler. Many of his stated priorities as pope also fell short: He failed to establish relations with China, heal the schism and reunite with the Orthodox Church, or reconcile with a group of breakaway, traditionalist Catholics.
There are several papal contenders in the wings, but no obvious front-runner — the same situation as when Benedict was elected after the death of John Paul. As in recent elections, some push is expected for the election of a Third World pope, with several names emerging from Asia, Africa and Latin America, home to about 40 percent of the world's Catholics.
The Vatican stressed that no specific medical condition prompted Benedict's decision, saying he remains fully lucid and took his decision independently.
"Any interference or intervention is alien to his style," Lombardi said.
The pope has clearly slowed down significantly in recent years, cutting back his foreign travel and limiting his audiences. He now goes to and from the altar in St. Peter's Basilica on a moving platform to spare him the long walk down the aisle. Occasionally he uses a cane.
As early as 2010, Benedict began to look worn out: He had lost weight and didn't seem fully engaged when visiting bishops briefed him on their dioceses. But as tired as he often seemed, he would also bounce back, enduring searing heat in Benin to caress a child and gamely hanging on when a freak storm forced him to cut short a speech during a youth festival in Madrid in 2011.
His 89-year-old brother, Georg Ratzinger, said doctors recently advised the pope not to take any more trans-Atlantic trips.
"His age is weighing on him," Ratzinger told the dpa news agency in Germany. "At this age, my brother wants more rest."
Benedict emphasized that to carry out the duties of being pope, "both strength of mind and body are necessary — strengths which in the last few months, have deteriorated in me."
"After having repeatedly examined my conscience before God, I have come to the certainty that my strengths due to an advanced age are no longer suited" to the demands of being the pope, he told the cardinals.
Although popes are allowed to resign, only a handful has done it — and none for a very long time.
The last pope to resign was Pope Gregory XII, who stepped down in 1415 in a deal to end the Great Western Schism, a dispute among competing papal claimants. The most famous resignation was Pope Celestine V in 1294; Dante placed him in hell for it.