ENCYCLICALS OF POPE JOHN XXIII No. Title Subject Date   1 Ad Petri cathedram On truth, unity and peace in a spirit of charity. 29 June 1959   2 Sacerdotii nostri primordia On St. John Vianney. 01 Aug 1959   3 Grata recordatio On the Eighth Century of the Independence of Portugal 26 Sept 1959   4 Princeps pastorum On the Mystical Body of Christ and the Church 28 Nov 1959   5 Mater et magistra On Sacred Scripture 15 May 1961   6 Aeterna Dei sapientia On St. Cyril, Patriarch of Alexandria 11 Nov 1961   7 Paenitentiam agere On the need for the practice of interior and exterior penance. 01 July 1962   8 Pacem in terris On establishing universal peace in truth, justice, charity, and liberty. 11 Apr 1963