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Joseph Ratzinger gives a theology lecture at the University of Freising in Germany during the summer semester in 1955.

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Published at 5:21 p.m. ET: Pope Benedict XVI always said he was first and foremost a teacher and a writer, and in his retirement he intends to pick up where he left off before he was called to church leadership, the Vatican said Monday. But is that a realistic expectation for a man universally known for his restless and questing intellect?

Roman Catholic Church law doesn't extensively account for a pope's abdication — among the hundreds of thousands of words in the Code of Canon Law, there's just one sentence: "If it happens that the Roman Pontiff resigns his office, it is required for validity that the resignation is made freely and properly manifested but not that it is accepted by anyone."

And since that hasn't happened in almost 600 years (or in more than 700 years depending on how you interpret history), there's no precedent for just what role, if any, a living ex-pope plays in the church.

What little is known came in a brief statement Monday from the Vatican, which said that when he leaves the papacy on Feb. 28, Benedict would move to Castel Gandolfo, the pope's summer residence in the Alban Hills a few miles south of Rome. Eventually, he will take up residence in a former cloistered monastery in the Vatican. What he will do there hasn't been clarified, but when he was elected pope in 2005, he said the job had interrupted his plans to retire and spend the rest of his life writing "in peace and quiet."

Beyond its obvious authority, the papacy is unique within the Catholic Church because of its temporal status — it doesn't come with the equivalent of tenure. So the moment he steps aside, Benedict will return to being just Joseph Aloisius Ratzinger, with no special authority or official prerogatives. 

"This is all very new territory," said Donald S. Prudlo, a historian at Jacksonville State University in Alabama and scholar of theology and church history at the Notre Dame Graduate School of Christendom College in Front Royal, Va. "No set of guidelines exist for an ex-pope, even including where he should live, what he should be called and what liturgical role he would play."

It's not even certain that Benedict will resume being an active cardinal — that would be up to the new pope. Prudlo told NBC News he thought it was "unlikely," saying he expected Benedict would want almost no public visibility in his declining years.

Even if Benedict, 85, does resume life as Cardinal Ratzinger, he's beyond the cutoff age of 80 to be eligible to vote, meaning he'll be locked out of the room when the College of Cardinals elects his successor as the leader of more than 1.2 billion Roman Catholics around the world.

But that doesn't mean he won't have influence should he choose to exercise it, and that could be tricky for his successor, said John Thavis, Rome bureau chief of Catholic News Service.

"The church has not really had a situation of two popes in many centuries," Thavis told NBC News from Vatican City. 

One reason is that the church has historically discouraged papal abdication out of concern about divided loyalties. Benedict's predecessor and mentor, John Paul II, declared that "there cannot be an 'emeritus pope.'"

"It is going to be hard for people to forget that Pope Benedict is still alive and he is still perhaps writing, still perhaps expressing himself," Thavis said. "I think it's going to fall to his successor to find a way to utilize this kind of expertise perhaps in a way that does not create new difficulties for the church."

But George Weigel, a Catholic theologian at the Ethics and Public Policy Center, a nonprofit religious research foundation, said Benedict "understands there is not room in the church for two popes."

"He will be very discreet about even writing new books," Weigel told NBC News.

Prudlo also predicted a smooth transition — perhaps the most orderly in centuries — because Benedict will be there to give the new pope the lay of the land.

"A new pope is often left flummoxed by the ins and outs of the office, usually taking years sometimes to gain a foothold," Prudlo said. "Having a 'senior pope,' for lack of a better word, would prove invaluable to easing into the throne of Peter."

Tracy Connor of NBC News contributed to this report.

Related:

• Pope Benedict XVI, citing deteriorating strength, will step aside Feb. 28
• Who's next? 8 cardinal contenders who could succeed Pope Benedict