Pope Benedict XVI gazed out on the crowd packing the piazza of a small Italian town. Below him lay the bones of Celestine V, the last pontiff to choose to retire; above rose sunlit crags where the "hermit pope" took refuge from a troubled mediaeval world.  A few weeks after that visit in July 2010 to Sulmona, in the Abruzzo mountains, the then 83-year-old Benedict told a fellow German he would not hesitate to become the first pope since Celestine in 1294 to resign of his own free will, if he was no longer able - "physically, psychologically and spiritually" - to meet the demands of running the billion-strong Catholic Church.  Did the example of Celestine's "Great Refusal" inspire his ageing successor to consider the alternative to death in office?  The working day Benedict spent in Sulmona, on July 4, 2010, was part of a typically busy schedule for the leader of one of the world's great faiths; he met hundreds of people and said mass for the 800th birthday of Pietro Angelerio, a monk who lived in local caves before and after his five troubled months as Pope Celestine V during a conflict between Church factions.  Some of Benedict's words that day may in retrospect betray a sense of weariness and a longing for a cloistered retirement.  In a homily to the crowd of 10,000 in the main square, he said: "A beautiful expression of St. Paul ... is also a perfect spiritual portrait of St. Peter Celestine: 'Far be it from me to glory, except in the Cross of our Lord Jesus Christ, by which the world has been crucified to me, and I to the world.'"
Pope Benedict shocks the world by saying he no longer has the mental and physical strength to cope with his ministry.