Quintilian, and J.S. Watson. Institutes of Oratory. Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book 8 Chapter 5.
“The ancient Latins called whatever they conceived in the mind sententia, ‘a thought’ (Quintilian VIII.5.1). Quintilian considers this a very appropriate usage, not only in the world of rhetoric but also in daily life. However, he would urge recognition of some sententiae which are particularly striking (Quintilian VIII.5.3). These may serve as elements of other figures of rhetoric, or they may stand on their own (Quintilian VIII.5.4). Quintilian notes that there are various classifications of different types of sententiae. Often the sententia is used for illustration rather than argument (Quintilian VIII.5.10). Another figure Quintilian describes as “noēma” - a thought “which they do not express, but wish to be understood” (Quintilian VIII.5.12). As with any figure of speech, the sententia can be used to good or bad effect. Quintilian illustrates several ineffective uses (Quintilian VIII.5.20). While some speakers are enthusiastic about sententiae, others avoid them. Quintilian favors moderate use (Quintilian VIII.5.25).