But the domain has shifted many times in subsequent ages. In the Middle Ages, rhetoric was concerned with sermons and letter- writing. During the Enlightenment, rhetoricians and natural philosophers studied the role of language and rhetoric in the making of scientific knowledge. Today, many rhetoricians argue that most speech and virtually all writing must be regarded as not only rhetorical, but as persuasive in some important ways. Discourse that affects an audience, that informs, moves, delights, and teaches, has a rhetorical aim. . . .
Rhetoric implies choices, for both the speaker or writer and the audience.
When we practice rhetoric we make decisions about our subject, audience, point of view, purpose, and message. . Furthermore, the audience must have a choice in responding to the message, must be able to adopt, modify, or reject it. . . . A burglar who holds a gun to my head . . . And the reader cooperates by trusting the reliability of the information. Cultures vary over space and over time.