“In view of the rapid expansion of national economies, particularly since the war, there is one very important social principle to which We would draw your attention. It is this: Economic progress must be accompanied by a corresponding social progress, so that all classes of citizens can participate in the increased productivity. The utmost vigilance and effort is needed to ensure that social inequalities, so far from increasing, are reduced to a minimum.
As Our Predecessor Pius XII observed with evident justification: “Likewise the national economy, as it is the product of the men who work together in the community of the State, has no other end than to secure without interruption the material conditions in which the individual life of the citizens may fully develop. Where this is secured in a permanent way, a people will be, in a true sense, economically rich, because the general well-being, and consequently the personal right of all to the use of worldly goods, is thus actuated in conformity with the purpose willed by the Creator.” (27) From this it follows that the economic prosperity of a nation is not so much its total assets in terms of wealth and property, as the equitable division and distribution of this wealth.This it is which guarantees the personal development of the members of society, which is the true goal of a nation’s economy.”
— Pope John XXIII, Mater Et Magistra, 1961.
And why this is relevant in the United States today: