Sealed inside the Sistine Chapel, restored to its original splendor during the pontificate of Pope John Paul II, 117 cardinals in their blood-red robes will soon gather to select his successor in the papal conclave - one of the world's most ancient and arcane electoral processes. It famously concludes with a puff of white smoke and the joyful Latin proclamation, Habemus papem: We have a pope.
Even as word of Pope John Paul's death was announced yesterday, the cardinals were preparing to journey to Rome from around the world for his funeral and pre-conclave meetings - the first will be tomorrow.
Then, no sooner than 15 days nor later than 20 days after the pope's death, the conclave will begin, following a script written nearly 1,000 years ago when cardinals were given sole authority to pick the pope.
At the outset, they swear oaths of secrecy upon pain of excommunication and vow loyalty to the next pope.
Belgium's Cardinal Godfried Danneels, one of the small group of cardinals considered by some commentators as papabili - the Italian word for papal frontrunners - broke off a visit to China and returned to Europe.
Cardinal Walter Kasper, a German who is president of the Vatican's commission for Christian unity, interrupted a trip to Bulgaria.
Four of the 11 American cardinals eligible to vote are already in Rome because of their positions in the Vatican bureaucracy, while the others, including Baltimore's Cardinal William H. Keeler, are finalizing their travel plans.
Though none of the 11 Americans is considered likely to become pope - the United States' superpower status militates against a successful candidacy - they could have a swing role, as in 1978 when Philadelphia's Cardinal John Krol championed Cardinal Karol Wojtyla of Krakow, Poland, who became John Paul II.
He was the first non-Italian pope in 455 years. With about three-quarters of the church's 1 billion members now living outside of Europe, there is a possibility that the next pope will come from church strongholds in Africa or Latin America. Among the names prominently mentioned are Cardinal Francis Arinze of Nigeria and Cardinal Oscar Andres Rodriguez Maradiaga of Honduras.
Europeans still account for half of the cardinals, however, and many papal scholars are convinced that the next pope will come from this group, and could be Italian.
Since Pope John Paul appointed all but three of the cardinal electors, there has been considerable speculation about whether the next pontiff will follow his conservative social and moral teachings, which have caused considerable division among church members. Such rifts have been particularly evident in the United States.
The term conclave derives from Latin words for "with a key" - and the notion of locking in electors comes from an actual historical event. In 1216, an angry public in Perugia, Italy, locked up cardinals who couldn't decide on a successor to Pope Innocent III.
Later, when the cardinals meeting at Viterbo, Italy, took nearly three years to elect Gregory X, the town's leaders confined the cardinals to the building where they were meeting in 1271, tore off the roof and limited them to a diet of bread and water.
Until the electors decide on a new pope, a little-known Spanish cardinal will be the most powerful man in the church.
Cardinal Eduardo Martinez Somalo, 78, who until his retirement in February 2004 led the Vatican's office supervising religious orders, serves as the camerlengo, or cardinal chamberlain. He is responsible for running the church until a new pope is elected.
Somalo will oversee planning of Pope John Paul's funeral and will prepare for the conclave.
The papal electors who will gather in the Sistine Chapel are a select group. Only cardinals under the age of 80 may participate, including Cardinal Keeler.
In the church's infancy, the process was more democratic. The pope, who is technically the bishop of the Diocese of Rome, was chosen like other bishops: The people and clergy of the diocese elected or chose the new bishop in the presence of bishops from other dioceses.
Traditionally, the new pope was not chosen from among existing bishops because a bishop was considered to be forever "married" to his diocese.
Technically, any baptized Catholic male can be elected pope, but no one but a cardinal has been chosen since 1378.
The election procedure remained essentially unchanged until 1975, when Pope Paul VI instituted the age limit of 80.
Pope John Paul II instituted important changes in 1996. For centuries, the cardinals in the conclave were confined to the papal palace, sleeping on hard cots in makeshift quarters, with sometimes nothing but a blanket separating one from another. There was a purpose for the Spartan accommodations: Uncomfortable cardinals worked more quickly.
But several years ago, Pope John Paul had Domus Sanctae Marthae, a hotel-style residence built for cardinals, where they will stay during the conclave. Some observers believe this could increase the length of deliberations.