Institutio Oratoria

Turning to those who regard rhetoric as an art, but not as a virtue, we find that Theodorus of Gadara is more cautious. For he says (I quote the words of his translators),

rhetoric is the art which discovers and judges and expresses, mith an elegance duly proportioned to the importance of all such elements of persuasion as may exist in any subject in the field of politics.

Similarly Cornelius Celsus defines the end of rhetoric as

to speak persuasively on any doubtful subject within the field of politics. Similar definitions are given by others, such for instance as the following:—

rhetoric is the power of judging and holding forth on such political subjects as come before it with a certain persuasiveness, a certain action of the body and delivery of the words.