Nicene and Post-Nicene Fathers, Vol. II:
On Christian Doctrine: Chapter 4

Chapter 4.—The Duty of the Christian Teacher.

6.  It is the duty, then, of the interpreter and teacher of Holy Scripture, the defender of the true faith and the opponent of error, both to teach what is right and to refute what is wrong, and in the performance of this task to conciliate the hostile, to rouse the careless, and to tell the ignorant both what is occurring at present and what is probable in the future.  But once that his hearers are friendly, attentive, and ready to learn, whether he has found them so, or has himself made them so, the remaining objects are to be carried out in whatever way the case requires.  If the hearers need teaching, the matter treated of must be made fully known by means of narrative.  On the other hand, to clear up points that are doubtful requires reasoning and the exhibition of proof.  If, however, the hearers require to be roused rather than instructed, in order that they may be diligent to do what they already know, and to bring their feelings into harmony with the truths they admit, greater vigor of speech is needed.  Here entreaties and reproaches, exhortations and upbraidings, and all the other means of rousing the emotions, are necessary.

7.  And all the methods I have mentioned are constantly used by nearly every one in cases where speech is the agency employed.