4 Over and above spiritual goods, however, there are many goods of the natural order over which the Church has no direct mission, although they flow as a natural consequence from her divine mission. The light of Catholic revelation is of such a nature that it diffuses itself with the greatest brilliance on every science. The force of the evangelical counsels is so powerful that it strengthens and firmly establishes the precepts of the natural law. The fruitfulness of the doctrine and morality taught by Jesus Christ is so limitless that providentially it sustains and promotes the material welfare of the individual, the family, and society. The Church, even in preaching Jesus Christ crucified, "stumbling block and foolishness to the world," has become the foremost leader and protector of civilization. She brought it wherever her apostles preached. She preserved and protected the good elements of the ancient pagan civilizations, disentangling from barbarism and educating for a new civilization the peoples who flocked to her maternal bosom. She endowed every civilization, gradually, but with a certain and always progressive step, with that excellent mark which is today universally preserved. The civilization of the world is Christian. The more completely Christian it is, the more true, more lasting and more productive of genuine fruit it is. On the other hand, the further it draws away from the Christian ideal, the more seriously the social order is endangered. By the very nature of things, the Church has consequently become the guardian and protector of Christian society. That fact was universally recognized and admitted in other periods of history. In truth, it formed a solid foundation for civil legislation. On that very fact rested the relations between Church and State; the public recognition of the authority of the Church in those matters which touched upon conscience in any manner, the subordination of all the laws of the State to the Divine laws of the Gospel; the harmony of the two powers in securing the temporal welfare of the people in such a way that their eternal welfare did not suffer.
Source: Il Fermo Proposito (Vatican.va)