101 Now all this array of priceless educational treasures which We have barely touched upon, is so truly a property of the Church as to form her very substance, since she is the mystical body of Christ, the immaculate spouse of Christ, and consequently a most admirable mother and an incomparable and perfect teacher. This thought inspired St. Augustine, the great genius of whose blessed death we are about to celebrate the fifteenth centenary, with accents of tenderest love for so glorious a mother: O Catholic Church, true Mother of Christians! Not only doest thou preach to us, as is meet, how purely and chastely we are to worship God Himself, Whom to possess is life most blessed; thou does moreover so cherish neighborly love and charity, that all the infirmities to which sinful souls are subject, find their most potent remedy in thee. Childlike thou are in molding the child, strong with the young man, gentle with the aged, dealing with each according to his needs of mind of body. Thou does subject child to parent in a sort of free servitude, and settest parent over child in a jurisdiction of love. Thou bindest brethren to brethren by the bond of religion, stronger and closer then the bond of blood .... Thou unitest citizen to citizen, nation to nation, yea, all men, in a union not of companionship only, but of brotherhood, reminding them of their common origin. Thou teachest kings to care for their people, and biddest people to be subject to their kings. Thou teachest assiduously to whom honor is due, to whom love, to whom reverence, to whom fear, to whom comfort, to whom rebuke, to whom punishment; showing us that whilst not all things nor the same things are due to all, charity is due to all and offense to none.
Source: Divini Illius Magistri (Vatican.va)