Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
But, as will appear in the course of this book, there is an infinite diversity of opinions among writers on [his subject, since some have added their own discoveries to those portions of the art which were still shapeless and unformed,
The first writer after those recorded by the poets who is said to have taken any steps in the direction of rhetoric is Empedocles. But the earliest writers of text-books are the Sicilians, Corax and Tisias, who were followed by another from the same island, namely Gorgias of Leontini, whom tradition asserts to have been the pupil of Empedocles.
He, thanks to his length of days, for he lived to a hundred and nine, flourished as the contemporary of many rhetoricians, was consequently the rival of those whom I have just mentioned, and lived on to survive Socrates.