20130401T0900-JOHN XXIII-HISTORICAL-1207696.jpg

Pope John XXIII signs his encyclical "Peace on Earth" ("Pacem in Terris") at the Vatican in this 1963 file photo. (CNS photo)
Pope John XXIII signs his encyclical "Peace on Earth" ("Pacem in Terris") at the Vatican in this 1963 file photo. (CNS photo)