Pope Benedict XVI's resignation has taken the world by surprise. However, the abdication of a pope is not unprecedented. There have been six others. Albeit, the last Pope to resign was Gregory XII in 1415.
The earliest pope to abdicate was Pontian, in 230. He had been sold into slavery and sent to Sardinia by the Romans and he wanted to avoid a power vacuum in the church. Since church and state were so intertwined during the Middle Ages political reasons played an important part in five popes stepping down from the Chair of Peter during this time period.
One of these popes was Celestine V. Pietro di Morrone was a Benedictine monk. He was elected in 1294 by Cardinals under duress from a Roman mob. They were demanding that the Cardinals elect a pope, since the See of Peter was vacant for two years at the time.
Celestine served only five months in office. He resigned and returned to his monastery knowing that he was not fit for the job. This was a tremendous act of humility on his part.
Benedict XVI can rightly claim Celestine V as his role model.
There is no doubt of Benedict's still ample intellect. His recent book on The Infancy Narratives: Jesus of Nazareth is proof of this. But, age has obviously taken its toll.
The pope is now almost 85 years old and Benedict has been obviously laying the groundwork for his resignation for some time. In an interview with Peter Sewald, in 2010, Benedict stated, "If a pope clearly realizes he is no longer physically and spiritually capable of handling the duties of his office, then he has a right and under some circumstances, also an obligation to resign."
The Code of Canon Law (1983) allows for this possibility. Canon 332§2 states, that a pope may resign if he does so "freely and his intention is duly manifested." With his public announcement to the world Benedict has fulfilled this requirement.
At the time of his election, in 2005, Benedict predicted a short papacy, since he was already 78 years old. He also referred to himself as a "little pope" in comparison to his predecessor John Paul II, who he called a "great pope."
Of late, it has become obvious to many Vatican watchers that the Pope's energy is declining. For example, he no longer walks down the aisles of St. Peter's Basilica. He is wheeled in, standing in a wagon-like vehicle by aides. There are also rumors that he has lost control of the unwieldy and often arcane Vatican bureaucracy; the management, of which, stands as a challenge even to a younger man.
And finally, rumors have it that, even the Italian bishops are seemingly ignoring his wishes. This is most especially obvious, in their reluctance to allow their priests to celebrate the traditional Mass (The Extraordinary Form) which Benedict himself implemented in a 2007 Motu Proprio, Summorum Pontificum (a document proclaimed on his own authority as the universal pastor of the Church).
Of course, many will recall the long papacy of John Paul II and his prolonged illness. Certainly, Benedict does not suffer the great physical disabilities of John Paul. Why, then didn't the former Pope resign? Because, many believe, he was making a heroic statement regarding the value of human life, even in sickness and old age. His example touched many. It was heroic.
Benedict, on the other hand, is teaching another lesson. He recognizes that he can no longer give his best to the Church, he loves. He is willingly stepping down so that another pope may more effectively lead the Church. Benedict's greatest gift to the Church and the world is his humility. His resignation will set a precedent for future popes. And, his humility will be spoken of until the end of time.