VATICAN CITY, VATICAN - MARCH 20:  Priests arrive in procession at St. Peter's Square during the Palm Sunday Mass celebrated by Pope Francis on March 20, 2016 in Vatican City, Vatican. Pope Francis on Sunday presided at the Procession and Mass for Palm Sunday, as the Church enters into the celebration of Holy Week. Palm Sunday commemorates the triumphal entry of Jesus into Jerusalem one week before His Passion, Death, and Resurrection.  (Photo by Franco Origlia/Getty Images)