For what concerns diversity of rites in the sacred liturgy, the Apostolic See has always made its position clear: not only it does not condemn diversity, but it eagerly and willingly grants to each nation the right to keep and preserve the legitimate customs and traditions of its forbears.
Pope Leo XIIIBut the supreme teacher in the Church is the Roman Pontiff. Union of minds, therefore, requires, together with a perfect accord in the one faith, complete submission and obedience of will to the Church and to the Roman Pontiff, as to God Himself.
Pope Leo XIIIHence from all we have hitherto said, it is clear beloved Catholics that we cannot approve the opinions which some [Protestants, Jews, and other heretics] comprise under the head of Americanism [freedom].
Pope Leo XIIIIt must be assumed and established as a principle, that the right of private property must be regarded as sacred. Wherefore, the law ought to favor this right and, so far as it can, see that the largest possible number among the masses of the population prefer to own property.... But if the productive activity of the multitude can be stimulated by the hope of acquiring some property... , it will gradually come to pass that, with the difference between extreme wealth and extreme penury removed, one class will become the neighbor to the other.
Pope Leo XIIIThe fact that God gave the whole human race the earth to use and enjoy cannot indeed in any manner serve as an objection against private possessions.
Pope Leo XIII