Then, in a rare gesture and sign of respect, the rows of bishops, some with tears in their eyes, removed their mitres. One prelate dabbed at his eyes with a handkerchief.
"Viva il papa!" someone in the crowd shouted as the pope slowly made his way down the steps of the altar, assisted by two clergymen. He then departed St. Peter's for the last time aboard a wheeled platform, sparing him the long walk down the aisle.
Ash Wednesday marks the start of Lent, the most solemn season on the church's liturgical calendar that ends with Holy Week, when the faithful commemorate the death of Christ and his resurrection on Easter Sunday. By this Easter, on March 31, the church will likely have a new pope.
In his final homily as pontiff, Benedict sent a clear message to his successor and those who will elect him of his hope for the future: a united church that isn't "defiled" by internal rivalries.
Each Christian, he said, is called to bear witness to the faith. "I think in particular of the attacks against the unity of the church, to the divisions in the ecclesial body," he said.
"Experiencing Lent in a more intense and evident ecclesial union, moving beyond individualisms and rivalries, is a humble and precious sign for those who have drifted from the faith or are indifferent to it."
Earlier in the day, the scene was festive as Benedict took the extraordinary step of speaking directly to the faithful about why he had broken with 600 years of tradition and decided to retire on Feb. 28.
"As you know, I have decided to renounce the ministry that the Lord gave to me on April 19, 2005," Benedict told thousands gathered for the traditional Wednesday general audience. "I did this in full liberty for the good of the church."