This year marks the 50th anniversary of the issuing of one of the most important papal encyclicals of the 20th Century, Paul VI's Populorum Progressio, on the development of peoples, writes Michael Costigan at La Croix International.
Its message retains its relevance today where aspirations for global justice are still so far from being realised.
In his biography of Paul VI, the late Peter Hebblethwaite quotes Professor Francois Perroux as calling it "a profound and original synthesis of the Ten Commandments, the Gospel teaching and the Declaration on Human Rights".
Like all of the other papal, council and synod documents on social justice published in the 126 years since Leo XIII's Rerum Novarum, it has its own context. On visiting or re-visiting it, one can usefully note the influences that led to its writing and the ways in which its lessons have been accepted, proclaimed, questioned, amended, neglected or updated over the past half-century.
The encyclical appeared in the heart of a decade of upheaval and change, in the Church and in society. Its issuing, on March 26, 1967, had been prepared for by the publishing of major documents from the Church leadership every second year from 1961 to 1967.
The first two were Pope John XXIII's social encyclicals Mater et Magistra, in 1961, and Pacem in Terris, in 1963.
Then, in 1965, came Vatican II's Pastoral Constitution on the Church in the modern world, Gaudium et Spes.
A number of experts contributed, either directly or indirectly, to the production of these three documents.
It can be said that they opened the way for, in some cases played a part in the composing, or at least helped to determine the content and orientation of Populorum Progressio.
What is common to these social justice apostles is that, during the 1960s, they all influenced in differing ways and degrees the attitude of the Holy See and in particular that of Pope Paul to the problem of global poverty and economic injustice.