"It is your duty, venerable brothers, sedulously to strive that the seed of heavenly doctrine be sown broadcast in the field of God, and that the teachings of the Catholic faith may be implanted early in the souls of the faithful, may strike deep root in them, and be kept free from the ruinous blight of error. The more the enemies of religion exert themselves to offer the uninformed, especially the young, such instruction as darkens the mind and corrupts morals, the more actively should we endeavor that not only a suitable and solid method of education may flourish but above all that this education be wholly in harmony with the Catholic faith in its literature and system of training, and chiefly in philosophy, upon which the direction of other sciences in great measure depends."
(Pope Leo XIII, "Inscrutabili Dei Consilio", 1878 A.D.)
"We have fallen upon times when a violent and well-nigh daily battle is being fought about matters of highest moment, a battle in which it is hard not to be sometimes deceived, not to go astray and, for many, not to lose heart. It behooves us, venerable brethren, to warn, instruct, and exhort each of the faithful with an earnestness befitting the occasion: that none may abandon the way of truth."
(Pope Leo XIII, "Sapientiae Christianae", 1890 A.D.)
"Watch earnestly lest deceitful men and the promoters of novelties continue to spread erroneous doctrines and false dogmas in your flock. Using the pretext of the common good, as is their custom, they take advantage of the credulity of those who are naive and rash, so that they may have them as blind servants and supporters in disturbing the peace of the kingdom and in overturning the order of society. Surely the fraud of these would-be teachers must be uncovered in clear words for the good and the instruction of the faithful. The fallacy of their thought must be refuted courageously everywhere with the words of divine scripture and the testimony of Church tradition."
(Pope Gregory XVI, "Cum Primum", 1832 A.D.)