The Holy Father and his aides in the Roman Curia began spiritual exercises this afternoon.
The Holy See announced that the Pope will hold no audiences or attend any public engagements until the retreat concludes Saturday morning.
Before praying the Angelus today with the crowds gathered in St. Peter's Square, the Holy Father asked the faithful to "please support me with your prayer, and I will be happy to do the same in the recollection of the retreat, invoking divine power on each one of you, on your families and your communities."
Cardinal Giacomo Biffi, retired archbishop of Bologna, Italy, will preach the retreat on the theme "Look for the things on high, where Christ is seated at the right hand of God: Think of the things on high, not of those on earth."
The exercises began in the Mater Redemptoris Chapel with the exposition of the Eucharist, vespers, an introductory meditation, adoration and Benediction.
Cardinal Biffi will preach three meditations each day. There will also be daily recitation of the Liturgy of the Hours, adoration and benediction.