Pacem in Terris — Encyclical of Pope John XXIII
In Peace on Earth, Pope John XXIII contends that peace can be established only if the social order set down by God is fully observed. Relying extensively on reason and the natural law tradition, John XXIII sketches a list of rights and duties to be followed by individuals, public authorities, national governments, and the world community. Peace needs to be based on an order “founded on truth, built according to justice, vivified and integrated by charity, and put into practice in freedom.”