Papal conclaves have changed over time, but they offer a fascinating window into both the Roman Catholic Church and the history of Europe.

Heads of state are chosen in many ways. Some come to power via revolution, some by lineal descent, some by orderly succession, and some by election. However, no stable method of choosing a head of state has been continuously in place longer than the election of a pope. And the pope is indeed a head of state. He’s not only the leader of the Roman Catholic Church and its bishop of Rome but the secular sovereign of the tiny country within Rome known as Vatican City. He is, in a sense, an elected monarch.
When the office of the pope, known as the papacy, is vacant — typically at the death of the latest incumbent; resignations have been extremely rare — members of the College of Cardinals gather from around the world to meet in a "conclave" in order to choose a new pope. (The term "conclave" comes from the Latin "cum clave," meaning "with a key," signifying the fact that, since 1274, the cardinal-electors are locked in seclusion until they agree on a new pope.)
In 1492, the Sistine Chapel, within Vatican City, began to be used for papal conclaves, and, since the 1846 gathering in the Quirinal Palace that elected Pius IX, all conclaves have been held there, beneath the marvelous paintings by Michelangelo, Botticelli and other eminent artists of the Italian Renaissance.
After the passing of the apostles, the bishops of Rome were chosen for many centuries by consensus of the priests and lay Christians of the city. In 1059, however, it was decided that only the "cardinal-priests" or principal clergy of the city could vote in papal elections. Nonetheless, since the pope is not merely bishop of Rome but the overall leader of the Catholic Church, other cities and regions also had a strong natural interest in the outcome of such votes.
Accordingly, beginning in the twelfth century, cardinals began to be appointed from among the Catholic clergy beyond Rome. In order to continue to comply with tradition, however, churches within the city would be assigned to them so that they would qualify, in theory at least, as priests of Rome. (This is still true of many, though not quite all, modern cardinals.) In 1970, Pope Paul VI decreed that cardinals who were more than 80 years of age or older could no longer participate as electors.
Many cardinals live and work in Rome as part of the church administrative apparatus called the "Curia," and they’re required to wait for at least 15 days before beginning a conclave so that cardinals from outlying areas have time to arrive in the city. However, they cannot postpone the beginning of a conclave more than 20 days; at that point, they’re required to commence proceedings even if some potential members of the conclave are still under way. (With modern air travel, obviously, this is rarely a factor. But it once was, and it led to occasional abuses.)
A two-thirds supermajority of the electors is required to choose a new pope. But even this isn’t quite enough. The person elected must formally accept the appointment; it’s a violation of church canon law to impose the office upon someone unwilling to receive it. Numerous attempts, or ballots, may be required before the cardinals agree upon their choice. Each time a vote is conducted, the individual ballots cast by the cardinals are burned.
If the required supermajority hasn’t been reached, chemicals are added — they replace the damp straw that was used for centuries — to ensure that the smoke issuing from the chapel’s chimney is black, thus informing the faithful (and the curious) gathered in St. Peter’s Square that no new pope has yet been chosen. When agreement has been reached, white smoke is sent up the chimney and, beginning with Benedict XVI’s own election in 2005, bells ring out so as to ensure that the news is unambiguous.
Papal conclaves are relatively rare occurrences, and they’re not only historic in and of themselves but are saturated with history and with pomp and traditions accumulated from antiquity, the Middle Ages and the Renaissance. They offer a fascinating glimpse into the European past, as well as into today’s Roman Catholic Church. We encourage our readers to follow the interesting and significant events of the next few days. With television and the Internet, we have the opportunity to see and hear things that very few among even the most faithful Catholic believers could personally witness before modern times.