Quintilian, and J.S. Watson. Institutes of Oratory. Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book 9 Chapter 3.
Quintilian aptly observes that language usage changes over time. Whether it is actually improving or not, the language does change (Quintilian IX.3.1). Regardless, some verbal figures have to do with the words themselves and some have to do with the organization of the phrases (Quintilian IX.3.2). Quintilian warns against using figures of speech too much or too little (Quintilian IX.3.4). He compares figures to seasoning in food. Common figures in Latin would include use of nouns in an unexpected gender or use of deponent or passive verbs where the active voice would be more customary (Quintilian IX.3.6-7). Less common may be a variety of verb tenses or unusual construction involving one part of speech used as another. Quintilian illustrates this with passages from numerous authors.
The process of change of part of speech leads rather naturally to use of phrases, clauses, or even sentences in unusual manners, such as when the speaker interrupts himself (Quintilian IX.3.23). Quintilian illustrates these larger syntactic figures from various authors. Some may include use of parallelism or repetition of the beginning or end of lines (Quintilian IX.3.29ff). The arrangement may even involve repetition within a long sentence or throughout a paragraph (Quintilian IX.3.43).
Quintilian does provide a useful catalog of various figures of syntax, beginning at 9.3.49. All serve to shape an overall message. The language rises and falls to create a sensible contour (Quintilian IX.3.54).
Quintilian further discusses figures created by omission of words, seeking “the merit of brevity or novelty” (Quintilian IX.3.58). The omission of words, as well as a use of similar sounding words in parallel sentences, may be very effective in balancing the phrasing of a speech (Quintilian IX.3.66). Use of very similar words so as to create a pun of sorts is a punishment which renders Quintilian out of sorts (Quintilian IX.3.70). Balance in language, however, is a good thing (Quintilian IX.3.75). Quintilian illustrates and names several ways that balance can be accomplished.
The line between a figure of words and a figure of thought may blur from time to time (Quintilian IX.3.88). An example would be an expression of doubt or one of personification. Both words and ideas are at work in these statements. Of particular use in this portion of Quintilian’s work is his frequent mention of other orators, their works, and the categories of figures which they provide. Finally, Quintilian observes that any figures of speech and thought should be used judiciously (Quintilian IX.3.100). Overuse or too little use are both failings in eloquent communication.