Not only, in strict truth, was marriage instituted for the propagation of the human race, but also that the lives of husbands and wives might be made better and happier. This comes about in many ways: by their lightening each other's burdens through mutual help; by constant and faithful love; by having all their possessions in common; and by the heavenly grace which flows from the sacrament.
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 XIIIIt is neither just nor human so to grind men down with excessive labour as to stupefy their minds and wear out their bodies.
Pope Leo XIIIIf unbridled licence of speech and writing be granted to all, nothing will remain sacred and inviolate; even the highest and truest mandates of nature, justly held to be the common and noblest heritage of the human race, will not be spared. Thus, truth being gradually obscured by darkness, pernicious and manifold error, as too often happens, will easily prevail.
Pope Leo XIIIThe sacred rites, although not instituted specifically for proving the truth of the dogmas of the Catholic Faith incontrovertibly, are effectively the living voice of Catholic Truth, the oft-sounded expression of it. For that very reason the true Church of Christ, even as she shows great zeal to guard inviolate those forms of divine worship - since they are hallowed and are not to be changed - sometimes grants or permits something novel in the performance of them in certain instances. This she does especially when they are in conformity with their venerable antiquity.
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 XIII