Woodstock Theological Center at Georgetown University. "Rather than electing the smartest man in the room, they should elect the man who will listen to all the other smart people in the Church."
Liberals have already begun calling for a pope that would be more open to reform.
"The current system remains an 'old boy's club' and does not allow for women's voices to participate in the decision of the next leader of our Church," said the Women's Ordination Conference, a group that wants women to be able to be priests.
The last pope to resign willingly was Celestine V in 1294 after reigning for only five months, his resignation was known as "the great refusal" and was condemned by the poet Dante in the "Divine Comedy". Gregory XII reluctantly abdicated in 1415 to end a dispute with a rival claimant to the papacy.
Lombardi said Benedict's stepping aside showed "great courage". He ruled out any specific illness or depression and said the decision was made in the last few months "without outside pressure". But the decision was not without controversy.
"This is disconcerting, he is leaving his flock," said Alessandra Mussolini, a parliamentarian who is granddaughter of Italy's wartime dictator. "The pope is not any man. He is the vicar of Christ. He should stay on to the end, go ahead and bear his cross to the end. This is a huge sign of world destabilisation that will weaken the Church."
Cardinal Stanislaw Dziwisz, secretary to the late Pope John Paul, said the former pope had stayed on despite failing health for the last decade of his life as he believed "you cannot come down from the cross."
While the pope had slowed down recently - he started using a cane and a wheeled platform to take him up the long aisle in St Peter's Square - he had given no hint recently that he was considering such a dramatic decision.
Elected in 2005 to succeed the enormously popular John Paul, Benedict never appeared to feel comfortable in the job.
"MIND AND BODY"
In his announcement, the pope told the cardinals that in order to govern "... both strength