Religious leader and world leaders paid tributes on Monday to Pope Benedict XVI, who is to resign on 28 February.
Chancellor Angela Merkel of Germany, his native country, describes him as one of the greatest religious thinkers of our time.
Prime Minister Mario Monti of Italy said he is greatly shaken by the resignation.
US President Barack Obama has extended his appreciation and prayers to the Pope.
Archbishop of Canterbury Justin Welby said Pope Benedict held the office with great dignity.
In Israel the Chief Rabbi praised his ability to reach out to other faiths.
But the Ramadhan Foundation, a British Muslim group, condemned his comments on Islam in the early years of his papacy.
Latin American successor?
There are suggestions the pope's successor should come from Latin America.
Andrew Downie, a Scottish freelance journalist based in Sao Paulo, told Morning Report that candidates have already emerged from Brazil.