14 We are indeed aware that the work of teaching the Catechism is unpopular with many because as a rule it is deemed of little account and for the reason that it does not lend itself easily to the winning of public praise. But this in Our opinion is a judgment based on vanity and devoid of truth. We do not disapprove of those pulpit orators who, out of genuine zeal for the glory of God, devote themselves to defense of the faith and to its spread, or who eulogize the saints of God. But their labor presupposes labor of another kind, that of the catechist. And so if this be lacking, then the foundation is wanting; and they labor in vain who build the house. Too often it happens that ornate sermons which receive the applause of crowded congregations serve but to tickle the ears and fail utterly to touch the hearts of the hearers. Catechetical instruction, on the other hand, plain and simple though it be, is the word of which God Himself speaks through the lips of the prophet Isaias: "And as the rain and the snow come down from heaven, and return no more thither, but soak the earth and water it, and make it to spring and give seed to the sower and bread to the eater: so shall my word be, which shall go forth from my mouth. It shall not return to me void, but it shall do whatsoever I please and shall prosper in the things for which I sent it." We believe the same may be said of those priests who work hard to produce books which explain the truths of religion. They are surely to be commended for their zeal, but how many are there who read these works and take from them a fruit commensurate with the labor and intention of the writers? The teaching of the Catechism, on the other hand, when rightly done, never fails to profit those who listen to it.
Source: Acerbo Nimis (Vatican.va)