Rhetorical Modes

rhetorical modes: this flexible term describes the variety, the conventions, and the purposes of the major kinds of writing. The four most common modes are exposition, argumentation, description, and narration. These writing modes are sometimes referred to as modes of discourse

"I find, since reading over the foregoing Narrative, that I have, in several instances, spoken in such a tone and manner, respecting religion, as may possibly lead those unacquainted with my religious views to suppose me an opponent of all religion. To remove the liability of such misapprehension, I deem it proper to append the following brief explanation."
                                                                       -Narrative of the Life of Frederick Douglass
                                                                                       by Frederick Douglass

Douglass is here explaining his purpose in writing the Appendix to his first autobiography. The Appendix is expository and persuasive; Douglass is explaining his rhetorical mode. He gives the purpose as explaining and clarifying, therefore his rhetorical mode is exposition. Douglass is explaining himself to alert the readers immediately to his views on religion; he does not want to risk anyone tuning him out because they misunderstand his religious views, so he explains himself.