Book 3 begins with a brief introduction, outlining the discussion to follow. Of the three elements of a speech, we have now completed our investigation of persuasion; style (that is, diction, or delivery; lexis in Greek) and arrangement remain.

Beginning with delivery, Aristotle explains: “[I]t is not enough to know what to say—one must also know how to say it” (182).

The speaker must know how to control his vocal volume, modulation, and rhythm, to suit the circumstances of his speech.

Linguistic style must be clear, befitting its subject, and contemporary-sounding. Although not an aspect of argumentation, these considerations could still impact the effectiveness of a speech:“Naturalness is persuasive, artifice just the reverse” (186). Along with the need for simple and natural language, metaphor is an essential tool to lend clarity to speech. Aristotle encourages beautiful-sounding metaphors that are proportional in scope to the object they represent (and hence natural). Aristotle also allows the use of epithet (descriptions affixed to names, such as “fleet-footed Achilles”), which he regards as a form of metaphor. Bad style can arise from four errors: poor use of compound words; strange vocabulary; poor use of epithets; and poor use of metaphor.