With Pope Benedict XVI now officially in retirement, Catholic cardinals from around the world begin on Friday the complex, cryptic and uncertain process of picking the next leader of the world's largest church.
Some details are still unclear, owing to Benedict's break with the tradition that papacies end with a pope's death, so these "princes of the Church" will first hold an informal session before traditional rounds of talks begin on Monday.
No front-runner stands out among the 115 cardinal electors - those aged under 80 - due to enter the Sistine Chapel for the conclave that picks the new pope, so discreetly sizing up potential candidates will be high on the cardinals' agenda.
They will also use the general congregations, the closed-door consultations preceding a conclave, to discuss future challenges such as better Vatican management, the need for improved communication and the continuing sexual abuse crisis.
Benedict ended his difficult eight-year reign on Thursday pledging unconditional obedience to whoever succeeds him to lead the world's 1.2 billion Catholics at one of the most problematic periods in the Church's 2,000-year history.
"The discussion we have in the congregations will be most important for the intellectual preparation" for choosing a pope, said Boston's Cardinal Sean O'Malley, adding the electors were already preparing spiritually for the vote by intense prayer.
"I would imagine each of us has some kind of list of primary candidates, and others secondary," said Cardinal Francis George of Chicago at a media briefing with O'Malley and another American cardinal, Daniel DiNardo of Galveston-Houston.
Most secretive election
Conclaves are among the world's most secretive elections, with no declared candidates, no open campaigning and electors who often do not know more than a few dozen men in the room.
Electors are sworn to secrecy about the actual voting itself.
George said cardinals consulted other electors before the conclave to learn more about possible choices, asking "what do you know about this candidate?" or "what kind of person is he?"
O'Malley, at his first conclave and already being mentioned in Italian media as a potential candidate, said he had been "using the Internet a lot" to read up on other cardinals.
Conclaves traditionally begin 15 days after the seat of St. Peter, as the papal office is called, becomes vacant. But that includes time for mourning and funeral ceremonies for a dead pope, so Benedict issued a decree allowing an earlier start.
From Monday, the cardinals will discuss how long they want to hold general congregations before going into the conclave; its name comes from the Latin term "cum clave" - with a key - to show they are locked away until a pope is chosen.
Cardinals over 80 cannot join them in the voting, but they are allowed to attend the general congregations and discuss the challenges to the Church with the electors.
Nothing is set yet, but the Vatican seems to be aiming for an election by mid-March so the new pope can be installed in office before Palm Sunday on March 24 and lead Holy Week services culminating in Easter the following Sunday.
Helicopter into history
The cardinals will not see a top secret report prepared for Pope Benedict on mismanagement and infighting in the Curia, the Church's bureaucracy.
But its three cardinal authors will be in the general congregations to advise electors on its findings.
"Since we don't really know what's in the report, I think we'll depend on the cardinals in the congregations to share with us what they think will be valuable for us to know to make the right decision for the future," O'Malley said.
In an emotional farewell to cardinals on Thursday morning in the Vatican's frescoed Sala Clementina, Benedict appeared to send a strong message to the cardinals and the faithful to unite behind his successor, whoever he turns out to be.
The appeal was significant because for the first time in history, there will be a reigning pope in the Vatican's Apostolic Palace and his retired predecessor living in a small monastery in the Vatican Gardens not far away.
Benedict left the Vatican by helicopter for the papal summer residence of Castel Gandolfo south of Rome to be far from the conclave and not influence it. He will move into the monastery when refurbishing is finished in about two months.