Citing failing strength of "mind and body," Pope Benedict XVI stunned close aides and 1 billion Catholics this week by becoming the first pope to retire in 600 years.
Pope Benedict XVI waves to the faithful gathered at the Colosseum during the Way Of The Cross procession on Good Friday April 6, 2012 in Rome, Italy. Photo by Franco Origlia/Getty Images
File: Pope Benedict XVI celebrates the holy mass on the Islinger Feld before an estimated 250,000 believers on September 12, 2006 in Regensburg, Germany.
Pope Benedict XVI carries the Paschal candle as he leads the Ceremony of the Light during the Holy Saturday Easter vigil mass at St. Peter's Basilica on April 7, 2012 in the Vatican. Photo by Franco Origlia/Getty Images
Pope Benedict XVI delivers a speech before leaving Germany at Lahr Black Forest airport on September 25, 2011 near Freiburg im Breisgau, Germany. Photo by Johannes Simon/Getty Images