Here is something that came out back in 2000 from the Pontifical Council for Justice and Peace called “The Social Agenda” and is a compendium of magisterial teaching of the Church (largely just quotations from various sources) arranged in categories for easy access. It appears to be a forerunner to the Compendium on the Social Doctrine of the Church that the same department released in 2005.
We (Cardinal Pole and I) have been discussing the authority and application of Pius IX’s Quanta Cura to the modern context.
I find it interesting, to say the least, that neither document from the PCJP quotes the teaching of any pope before Leo XIII (with one exception: The Social Agenda quotes a line from Gregory the Great). (Just as an aside, Quanta Cura p.3 is affirmed by the Catechism of the Catholic Church in just one instance: in footnote 39 to paragraph 2109 which states taht “The right to religious liberty can of itself be neither unlimited nor limited only by a “public order” conceived in a positivist or naturalist manner.”)
Some might say the great watershed in Catholic Social teaching came with Vatican II, but it is undeniable that in fact Leo XIII marked the real turning point. I would contend that the turning point was not a change in the faith and morals of the Church, but a readiness on the part of the Church to address her faith and morals, for the first time, to that society which today we would call “modern”. In fact, Leo is usually accredited with inventing the idea of a “social encyclical”.
For my part, I find that Leo XIII, in Immortale Dei (1885) goes a very long way to providing the positive teaching with regard to the State which “connects the dots” between the condemnations of Pius IX in Quanta Cura and the seemingly opposite affirmations of the Second Vatican Council and the modern popes. Even Immortale Dei requires reading within its context, but it at least gives a measured foothold on which to carry out the dialogue between what goes before and what comes after.
Only when all the dots are connected – not leaving any of the dots out (whether they date from 1864, 1885, 1965 or 2008) – will an overall coherant picture be formed.