Institutio Oratoria

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.