Pope John Paul II
1. The social concern of the Church, directed towards an authentic development of man and society which would respect and promote all the dimensions of the human person, has always expressed itself in the most varied ways. In recent years, one of the special means of intervention has been the Magisterium of the Roman Pontiffs which, beginning with the Encyclical Rerum Novarum of Leo XIII as a point of reference,1 has frequently dealt with the question and has sometimes made the dates of publication of the various social documents coincide with the anniversaries of that first document.
The Popes have not failed to throw fresh light by means of those messages upon new aspects of the social doctrine of the Church. As a result, this doctrine, beginning with the outstanding contribution of Leo XIII and enriched by the successive contributions of the Magisterium, has now become an updated doctrinal "corpus." It builds up gradually, as the Church, in the fullness of the word revealed by Christ Jesus3 and with the assistance of the Holy Spirit (cf. Jn 14:16, 26; 16:13-15), reads events as they unfold in the course of history. She thus seeks to lead people to respond, with the support also of rational reflection and of the human sciences, to their vocation as responsible builders of earthly society.
2. Part of this large body of social teaching is the distinguished Encyclical Populorum Progressio, which my esteemed predecessor Paul VI published on March 26, 1967.