Augustine addresses the use and learning of rhetoric in Book IV of his work De Doctrina Christiana ("On Christian Doctrine"). He introduces rhetoric as "the verbal expression of thought." In his work, Rhetorica, the Latin author, Cicero in more than one passage defined rhetoric as "speaking in a persuasive manner."
Augustine was greatly influenced during his education and in his adolescence by Cicero, especially one particular work by Cicero that no longer exists, Hortensius. Augustine stated that rhetoric is neither good nor bad in itself, but can be used to effectively defend both what is true and what is false. He goes on to point out that if one wishes to defend truth, it is crucial to be eloquent in order to refute what is false through the power of oratory.
The orator must formulate his speech in such a way as to instruct the audience, hold their attention, and to win. By this, Augustine meant that the orator must not only instruct the audience in what is true, he must also convince them of the truth so that they will act on it. Augustine carefully listed both the goals and the pitfalls of instructional rhetoric.
First of all, clarity and understanding are the primary goals. A rhetor should be able to adjust his manner of speaking to the abilities of his audience. For example, if necessary the rhetor should be able to abandon the niceties of proper grammar and speech in order to make the subject more accessible to the audience. When speaking or preaching to an assembly (such as in a church), it is not proper or customary for the audience to interrupt and ask questions.
It is the role of the rhetor to assist the listeners by anticipating their questions before they arise, and to answer them. To reach the most people, the subject should be presented in several ways. Once it is clear that the point has been made and the audience has reached understanding, the rhetor must move on. If he does not, he will lose the attention of his audience.
Augustine was an excellent example of the noble art of rhetoric, especially to his own people in the church at Hippo. His influence can be seen even today in the modern liberal arts education. He said, "In the case of a keen and ardent nature, fine words will come more readily through reading and hearing the eloquent than by pursuing the rules of rhetoric."
Experts who have analysed the sermons and writings of Augustine report that his background rhetoric is frequently able to be detected, particular in his use of verbal ornaments, allegory, figures of speech, parables, metaphors, antitheses, and the rhythmic endings to sentences.