In a historic match-up of papacies past and present, Pope Francis and emeritus Pope Benedict XVI will honor Popes John XXIII and John Paul II in the first ever canonization of two popes. For such a momentous occasion, the ceremony is actually quite short and surprisingly straightforward, with the added benefit that the relics of the two new saints will be presented for universal veneration by the church for the first time. Here are five things to look for - though beware, the rite is celebrated mostly in Latin, the official language of the Catholic Church.
1. THE CEREMONY
The preliminary part of the ceremony begins at around 0700 GMT with prayers, hymns and culminates with the chanting of the hypnotic Litany of Saints, the roll call of the church's saints, each one followed by the refrain ''Ora pro nobis,'' or ''Pray for us.''
After Pope Francis and concelebrants process to the altar, the canonization rite begins immediately.
The head of the Vatican's saint-making office, Cardinal Angelo Amato, asks the pope three separate times to include John XXIII and John Paul II among the saints. In the rite for beatification, there is only one such petition. The three repeated requests for canonization ''signify the importance of this celebration,'' noted the Vatican spokesman the Rev. Federico Lombardi.
2. THE PRONOUNCEMENT
Pope Francis then says: ''For the honor of the Blessed Trinity, the exaltation of the Catholic faith and the increase of the Christian life, by the authority of our Lord Jesus Christ, and of the holy Apostles Peter and Paul, and our own, after due deliberation and frequent prayer for divine assistance, and having sought the counsel of many of our brother bishops, we declare and define Blessed John XXIII and John Paul II be saints and we enroll them among the saints, decreeing that they are to be venerated as such by the whole church. In the name of the Holy Father, and of the Son, and of the Holy Spirit.''
3. THE RELICS
Relics of the two new saints are then brought to the altar. In the case of John Paul, the same relic - his blood - used for his 2011 beatification is being used. For John XXIII, a small piece of skin taken after his body was exhumed for his 2000 beatification is being used. Relics - the physical remains of a new saint or things he or she