Although Aristotle, with philosophical caution, was careful to state that
the function of rhetoric is not to persuade but to discover the available
means of persuasion,[39] his successors were more direct, if less
accurate. Hermagoras affirms that the purpose of rhetoric is
persuasion,[40] and Dionysius of Halicarnassus defines rhetoric as the
artistic mastery of persuasive speech in communal affairs.[41] But the
anonymous author of the Latin rhetorical treatise addressed to C.
Herennius, long believed to be the work of Cicero, qualifies this by
defining the purpose of rhetoric as "so to speak as to gain the assent of
the audience as far as possible."[42] And the sum of Cicero's opinion is
that the office of the orator is to speak in a way adapted to win the
assent of his audience.[43] In his definition of rhetoric Quintilian makes
a departure from the habits of his predecessors by defining rhetoric as
the _ars bene dicendi_, or good public speech.[44] Here the _bene_ implies
not only effectiveness, but moral worth; for in Quintilian's conception
the orator is a good man skilled in public speech, and there are times
when, as in the case of Socrates, who refused to defend himself, to
persuade would be dishonorable.[45] Quintilian's precepts, however, are
more in line with Aristotle than his definition. He busies himself
throughout twelve books in teaching his students how to use all possible
means to persuasion. The consensus of classical opinion, then, agrees that
the purpose of rhetoric is persuasive public speaking.



2. Subject Matter


If then the purpose of classical rhetoric was to come as near persuasion