1 How great is the skill required for the teacher in contending earnestly for the truth, has been sufficiently set forth by us. But I have to mention one more matter beside this, which is a cause of numberless dangers, though for my own part I should rather say that the thing itself is not the cause, but they who know not how to use it rightly, since it is of itself a help to salvation and to much good besides, whenever you find that earnest and good men have the management of it.
What then, do I mean by this? The expenditure of great labor upon the preparation of discourses to be delivered in public. For to begin with, the majority of those who are under the preachers' charge are not minded to behave towards them as towards teachers, but disdaining the part of learners, they assume instead the attitude of those who sit and look on at the public games; and just as the multitude there is separated into parties, and some attach themselves to one, and some to another, so here also men are divided, and become the partisans now of this teacher, now of that, listening to them with a view to favor or spite.
And not only is there this hardship, but another quite as great. For if it has occurred to any preacher to weave into his sermons any part of other men's works, he is exposed to greater disgrace than those who steal money. Nay, often where he has not even borrowed anything from any one, but is only suspected, he has suffered the fate of a thief. And why do I speak of the works of others when it is not permitted to him to use his own resources without variety? For the public are accustomed to listen not for profit, but for pleasure, sitting like critics of tragedies, and of musical entertainments, and that facility of speech against which we declaimed just now, in this case becomes desirable, even more than in the case of barristers, where they are obliged to contend one against the other.
A preacher then should have loftiness of mind, far exceeding my own littleness of spirit, that he may correct this disorderly and unprofitable pleasure on the part of the multitude, and be able to lead them over to a more useful way of hearing, that his people may follow and yield to him, and that he may not be led away by their own humors, and this it is not possible to arrive at, except by two means: indifference to their praise, and the power of preaching well.
Source: On the Priesthood (New Advent)