39 Was there ever a time, Venerable Brethren, when there was greater call than now for us all, lay and cleric alike, to imbibe the spirit of this "Greatest of Doctors"? For there are many contumacious folk now who sneer at the authority and government of God, Who has revealed Himself, and of the Church which teaches. You know - for Leo XIII warned us - "how insistently men fight against us; You know the arms and arts they rely upon." It is your duty, then, to train as many really fit defenders of this holiest of causes as you can. They must be ready to combat not only those who deny the existence of the Supernatural Order altogether, and are thus led to deny the existence of any divine revelation or inspiration, but those, too, who - through an itching desire for novelty - venture to interpret the sacred books as though they were of purely human origin; Those, too, who scoff at opinions held of old in the Church, or who, through contempt of its teaching office, either reck little of, or silently disregard, or at least obstinately endeavor to adapt to their own views, the Constitutions of the Apostolic See or the decisions of the Pontifical Biblical Commission. Would that all Catholics would cling to St. Jerome's golden rule and obediently listen to their Mother's words, so as modestly to keep within the bounds marked out by the Fathers and ratified by the Church.
Source: Spiritus Paraclitus (Vatican.va)