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.”