It was also translated extensively into European vernacular languages and continued to serve as the standard schoolbook text on rhetoric during the Renaissance.
[2] The Rhetorica ad Herennium can be seen as part of a liberal populist movement, carried forward by those, like L. Plotius Gallus, who was the first to open a school of rhetoric at Rome conducted entirely in Latin.
Book 4 of the Rhetorica ad Herennium's systematic treatment of Latin oratory style identifies two categories of rhetorical devices, or Figures.
Although these figures have been in use in rhetoric throughout history, the Rhetorica ad Herennium was the first text to compile them and discuss the effects they have on an audience.
The author groups these three figures together, stating that disjunction is best suited for limited use to convey elegance while one should use conjunction more frequently for its brevity.
Asyndeton is the presentation of concise clauses connected without conjunctions, which the Rhetorica ad Herennium claims creates animation and power in the speech.
The author defines metaphor as the application of one object to another due to some indirect similarity, and allegory as the implication of multiple meanings to a phrase beyond the actual letter of the words used.
The Figures of Thought include: Distribution, which assigns specific roles to a number of objects or people in order to identify their place in the structure of the argument, and frankness of speech, in which the speaker exercises his right to speak freely despite the presence of superiors.
Dialogue is used as a figure of thought when the speaker puts words in the mouth of his opponent for the sake of rhetorical conversation to illustrate his point.
Comparisons point out similar traits in different people or objects, while exemplification is the citing of something done in the past along with the name of the person or thing that did it.
Emphasis leaves more to be suspected about a topic than what is actually said, while conciseness is the precise expression of a thought using the least amount of language possible.
[5] At the request of William of Santo Stefano, the Rhetorica ad Herennium was translated into Old French by John of Antioch in 1282.