The importance of rhetoric in ancient education and public life is
reflected in the wealth of rhetorical treatises composed by classical
orators and teachers of oratory. An understanding of classical rhetoric
can be gained only by a study of its purpose, subject-matter, and content.
The _Rhetoric_ of Aristotle has sometimes been called the first rhetoric.
In two senses this is not true. Aristotle's contribution to rhetorical
theory is not a text-book, but a philosophical treatise, a part of his
whole philosophical system. In the second place, even in his day there
were many text-books of rhetoric with which Aristotle finds fault for
their incomplete and unphilosophical treatment. If the _Rhetoric ad
Alexandrum_, at one time falsely attributed to Aristotle and incorporated
in early editions of his works, is typical of the earliest Greek
text-books, the failure of the others to survive is fortunate. Aristotle's
rhetorical theories superseded those of the early text-books, and through
the influence of his _Rhetoric_ and the teaching of his pupil Theophrastus
set their seal on subsequent rhetorical theory. In practice as distinct
from theory, Isocrates probably had an influence more direct and intense,
but briefer.


Definitions

"Rhetoric," says Aristotle, "may be defined as a faculty of discovering
all the possible means of persuasion in any subject."[37]

He compares rhetoric with medicine; for the purpose of medicine, he
believes, is not "to restore a person to perfect health but only to bring
him to as high a point of health as possible."[38] Neither medicine nor
rhetoric can promise achievement, for in either case there is always
something incalculable.