"After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry.This makes him the first pope to resign from office rather than die in it since 1415, when Pope Gregory XII resigned in the midst of a conflict within the church, a period when 3 different men claimed to be the Pope, Gregory XII in Rome, Benedict XII in Avignon, France, and John XXIII in Pisa:
"I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering.
"However, in today's world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognise my incapacity to adequately fulfil the ministry entrusted to me."
...The Council of Constance finally resolved the situation. Gregory XII appointed Carlo Malatesta and Cardinal Giovanni Dominici of Ragusa as his proxies. The cardinal then convoked the council and authorized its succeeding acts, thus preserving the formulas of Papal supremacy. Thereupon on 4 July 1415, Malatesta, acting in the name of Gregory XII, pronounced the resignation of the Pope, which the cardinals accepted. According to prior agreement, they agreed to retain all the cardinals that had been created by Gregory XII, thus satisfying the Correr clan, and appointed Gregory XII Bishop of Frascati, Dean of the Sacred College of Cardinals and perpetual legate at Ancona. The Council then set aside Antipope John XXIII (1410–15), the successor of Alexander V. After the former follower of Benedict XIII appeared, the council declared him deposed; and the Great Schism was ended. A new Roman pontiff, Pope Martin V, was not elected before Gregory's death.