Some relevant and moderately favored definitions of rhetoric

These are pasted from my writing journal. I'm not even sure where I got some of them (shhh, don't tell anyone). But they are still good:

"rhetorical study, in its strict sense, is concerned with the modes of persuasion. Persuasion is clearly a sort of demonstration, since we are most fully perusaded when we consider a thing to have been demonstrated."
from http://www.stanford.edu/dept/english/courses/sites/lunsford/pages/defs.htm

Kenneth Burke: "Rhetoric is rooted in an essential function of language itself, a function that is wholly realistic and continually born anew: the use of language as a symbolic means of inducing cooperation in beings that by nature respond to symbols."

George Campbell: [Rhetoric] is that art or talent by which discourse is adapted to its end. The four ends of discourse are to enlighten the understanding, please the imagination, move the passion, and influence the will.
what about discourse as Inquiry?

Gerard A. Hauser: Introduction to Rhetorical Theory (1986)
Rhetoric is an instrumental use of language…. One person engages another person in an exchange of symbols to accomplish some goal. It is not communication for communication's sake. Rhetoric is communication that attempts to coordinate social action. For this reason, rhetorical communication is explicitly pragmatic. Its goal is to influence human choices on specific matters that require immediate attention.

Sappho
Persuasion is Aphrodite's daughter: it is she who beguiles our mortal hearts (frg 90).
Poems and Fragments. Trans. Josephine Balmer. Seacaucus: Meadowland 1984.