While meeting with his cardinals this week, Pope Benedict XVI did something historical. He resigned. According to History Professor Joelle Rollo-Koster, who wrote the following article, popes almost never resign their positions; instead, they die in office. Many observers may wonder if a pope is even allowed to resign. Under certain conditions, he is, and it is entirely because of one man, Pope Celestine V (1209-1296), the only other pope to have stepped down.

Why would something that happened more than 700 years ago matter? Because the modern papacy is based on structures and rules established during the Middle Ages. The word “pope,” designating the successor to Saint Peter, was put into usage during the early Middle Ages, first to designate all bishops and then, starting in the 6th century, to designate the bishop of Rome. By the 10th century Pope Gregory VII stated that the title would be reserved to the successor of Saint Peter “because he is unique in the world.”

To unravel the history of the first papal abdication entails a visit to the early history of the papacy itself and themes of political bargaining and violence. Pietro de Morrone, Pope Celestine V, was elevated to the tiara at Perugia on July 5, 1294. He was the son of peasants who, after early callings for a religious life, became dissatisfied with his experiences as a Benedictine monk and a priest. He eventually chose to follow the poor lifestyle of a hermit, settling on Mount Morrone, east of Rome. Pilgrims soon followed him, his reputation as a holy man grew, and he founded several religious houses to accommodate his followers, abandoning somewhat his dream of an eremitic life. The death of Pope Nicolas IV on April 4, 1292 initiated a long negotiation for the nomination of the future pope, fueled by rivalries between the great Roman families of Colonna, Savelli, and Orsini, and the French Anjou and Aragonese dynasties. The cardinals could not agree on a successor. At the suggestion of Charles II d’Anjou, who represented French interests in the realms of Naples and Sicily, Morrone wrote a letter to the cardinals castigating their delays. His letter garnered him the papal election.

Ill equipped for his office, Celestine (who chose his name after “celestial power”) was controlled by Charles d’Anjou who installed him not in Rome but in Naples, where he lived in a cell at the Castel Nuovo. Celestine contemplated resignation. He reintroduced the original conclave regulations created by Gregory X in 1274 to organize and institutionalize the ill-defined nomination process of a pontiff, and ordered that they be followed even in the case of a papal abdication. Canon lawyers supported his wish.

For a good part of the Middle Ages and based on scriptures, the prospect of an abdication had always been considered irrelevant. 1 Cor 7: 20 states, “Each person should remain in the situation they were in when God called them,” making abdication impossible. But the pope is a bishop and the resignation could be approached indirectly. Pope Innocent III in the early 13th century had established that a bishop could resign in sickness, physical or mental impediment; because of criminal activities; if he was disliked, obstinate, or irritated people; or if he chose to enter cloistered life. On December 10, 1294, Celestine abdicated in front of his cardinals, claiming illness, incompetence, and his wish to return to his eremitic life. A papal abdication became legitimate under canon law when Celestine’s successor, Boniface VIII, decreed in Liber sextus decretalium, 1: 7,1, “that the Roman Pontiff may freely resign.” Celestine died of a natural death on May 19, 1295, while imprisoned by Boniface VIII at the Castle of Fumone.

Thanks to Celestine’s efforts to formalize rules for papal abdication seven centuries ago, Pope Benedict’s resignation is not expected to be challenged or face other insurmountable hurdles.