The Pope explained that the significance of this feast will be underlined by the attendance in Rome of "a special delegation sent by the ecumenical patriarch of Constantinople," Bartholomew I. Within the Orthodox Church the patriarch is considered the "first among equals."
The Holy Father reciprocates by sending a delegation to the See of the Patriarchate of Constantinople (in present-day Istanbul, Turkey) on Nov. 30, the feast of St. Andrew, founder of the Church in Constantinople and brother of St. Peter, Bishop of Rome.
Benedict XVI's words were heard, amid much applause, by tens of thousands of people who filled St. Peter's Square to pray the midday Angelus with him.
The highlight of this Wednesday's liturgical solemnity of the two apostles will be the Mass celebrated in St. Peter's Basilica, beginning at 9:30 a.m.
"It will be a significant occasion to underline the unity and catholicity of the Church," said the Pope from the window of his study.
He invited "the faithful of Rome -- who venerate the holy apostles Peter and Paul as their special patrons -- pilgrims and the whole People of God to invoke heavenly protection on the Church and her pastors."
Last year, Bartholomew I himself attended the Mass, at which Pope John Paul II presided, to commemorate 40 years since the historic 1964 embrace between Pope Paul VI and Ecumenical Patriarch Athenagoras I in Jerusalem. The Second Vatican Council was under way at the time.
Later, on Dec. 7, 1965, one day before the conclusion of the Council, Paul VI and Athenagoras I presented a joint declaration to deplore and lift the mutual "anathemas," pronounced in 1054, which helped trigger the schism between the Eastern and Western Churches.