It is not the part of prudence to neglect that which antiquity in its long experience has approved and which is also taught by apostolic authority.
Pope Leo XIIIIt is clear that the main tenet of socialism, community of goods, must be utterly rejected, since it only injures those whom it would seem meant to benefit, is directly contrary to the natural rights of mankind, and would introduce confusion and disorder into the commonweal. The first and most fundamental principle, therefore, if one would undertake to alleviate the condition of the masses, must be the inviolability of private property.
Pope Leo XIIITo the shepherds alone was given all power to teach, to judge, to direct; on the faithful was imposed the duty of following their teaching, of submitting with docility to their judgment, and of allowing themselves to be governed, corrected, and guided by them in the way of salvation. Thus, it is an absolute necessity for the simple faithful to submit in mind and heart to their own pastors, and for the latter to submit with them to the Head and Supreme Pastor.
Pope Leo XIIIFor 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 XIIIThese most crafty enemies [the devils] have filled and inebriated with gall and bitterness the Church, the spouse of the Immaculate Lamb, and have laid impious hands on Her most sacred possessions. In the Holy Place itself, where has been set up the See of the most holy Peter and the Chair of Truth for the light of the world, they have raised the throne of their abominable impiety, with the iniquitous design that when the Pastor has been struck, the sheep may be scattered.
Pope Leo XIIIThe empire of Christ the King includes not only Catholic nations, not only baptized persons who, though of right belonging to the Church, have been led astray by error, or have been cut off from her by schism, but also all those who are outside the Christian faith: so that truly the whole of mankind is subject to the power of Jesus Christ.
Pope Leo XIII