Quintilian, and J.S. Watson. Institutes of Oratory. Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book 9 Chapter 2.
In book 9 chapter 2 Quintilian continues his discussion of figures of speech. He observes that while he tends to be minimal in classification of figures other rhetoricians divide the categories quite extensively (Quintilian IX.2.1). The art of speaking well doubtless uses all sorts of devices (Quintilian IX.2.3). However, in general, Quintilian is more ready to use these attractive features of language than to analyze them. He illustrates the very common interrogation, noting that there are many forms of questioning which could be organized into categories. Likewise, replies can be categorized (Quintilian IX.2.11). It is further quite possible to ask and answer questions so as to create an opinion in the minds of the hearers (Quintilian IX.2.26).
Closely related is an invention of entire characters and dialogs in a speech (Quintilian IX.2.30). This practice allows the speaker to place positive or negative statements into the mouths of characters, using irony, sarcasm, and the like in ways which may otherwise not be accepted by the listener (Quintilian IX.2.48). Another common figure is self-interruption. This leaves an idea unexpressed but still makes it clear, as the listener will fill in any gaps (Quintilian IX.2.54). Another valuable figure is that of making our speech seem accidental and unprepared. This can reduce the suspicions of our opponents (Quintilian IX.2.60). A very common figure is speech which does not state the conclusion but leads the hearers to make a conclusion (Quintilian IX.2.65). Quintilian urges against excessive use of figures. They are not the main proofs of a case (Quintilian IX.2.72). Unfortunately, schools of declamation may tend to depend on figures of speech or use them regardless of their appropriateness (Quintilian IX.2.81). This prepares orators poorly. Quintilian details ways to overcome these defects in training. Quintilian finally lists a number of figures of speech or thought classified by Celsus (Quintilian IX.2.102ff) and others.