Pope Benedict XVI says goodbye

In this image taken from video as Pope Benedict XVI delivers his final greetings to the assembly of cardinals at the Vatican, Feb. 28, 2013, before he retires in just a few hours. Benedict urged the cardinals to work in unity and promised his "unconditional reverence and obedience" to his successor in his final words to his cardinals in a poignant and powerful farewell before he becomes the first pope in 600 years to resign.

Pope Benedict XVI waves to clergy and supporters as he departs the Vatican for the final time as pontiff, Feb. 28, 2011.

A helicopter with Pope Benedict XVI onboard leaves the Vatican in Rome, Feb. 28, 2013.

The helicopter taking Pope Benedict XVI to Castel Gandolfo leaves the Vatican in Rome, Feb. 28, 2013.

In this photo provided by the Vatican newspaper L'Osservatore Romano, Pope Benedict XVI, center, delivers his message on the occasion of his farewell meeting to cardinals, at the Vatican, Feb. 28, 2013.

In this photo provided by the Vatican newspaper L'Osservatore Romano, Pope Benedict XVI delivers his message on the occasion of his farewell meeting to cardinals, at the Vatican, Feb. 28, 2013.

In this photo released by the Vatican newspaper L'Osservatore Romano, Pope Benedict XVI receives German politician Horst Seehofer and his wife Karin during a private audience which followed his last general audience, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI gestures during his final general audience in St.Peter's Square at the Vatican, Feb. 27, 2013. Pope Benedict XVI basked in an emotional sendoff Wednesday at his final general audience in St. Peter's Square, recalling moments of "joy and light" during his papacy but also times of great difficulty. He also thanked his flock for respecting his decision to retire.

Pope Benedict XVI's personal secretary George Gaenswein, left, wipes his eye as the Pope delivers his message during his last general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI greets pilgrims in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI talks to his personal secretary George Gaenswein as he leaves at the end of his general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI, followed by his personal secretary Archbishop Georg Gaenswein, leaves after celebrating his last general audience, in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI leaves after celebrating his final general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI opens his arms during his final general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI reads a message during his final general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI waves to pilgrims in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI waves to faithful during his final general audience in St.Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI is seen leaving St. Peter's Square on his pope-mobile after his last general audience, at the Vatican, Feb. 27, 2013.

Faithful are reflected in the roof of Pope Benedict XVI's pope-mobile as he arrives with his personal secretary Archbishop Georg Gaenswein, right, for his last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI greets pilgrims at the end of his general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI is seen in his pope-mobile, escorted by security, during his last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI waves from his pope-mobile as he is driven through the crowd during his last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI waves as he arrives for his last general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

A Vatican Swiss guard stands in front of St. Peter's Basilica at the Vatican, Feb. 27, 2013.

Pope Benedict XVI kisses a baby handed up to him by his secretary George Ganswein as he greets pilgrims in St. Peter's Square at the Vatican, Feb. 27, 2013.

Faithful gather in St. Peter's Square at the Vatican, Feb. 27, 2013.

Pope Benedict XVI is driven through the crowd in his pope-mobile as he arrives to celebrate his last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI kisses a baby during his general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Faithful gather for Pope Benedict XVI's last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Pope Benedict XVI is seen on a giant screen during his last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.

Cardinals applaud during Pope Benedict XVI's final general audience in St. Peter's Square at the Vatican, Feb. 27, 2013.

Nuns attend Pope Benedict XVI's last general audience in St. Peter's Square, at the Vatican, Feb. 27, 2013.