Continuing his study of the humanities, he became in 1628 professor of rhetoric at Innsbruck, and in 1635 at Ingolstadt, whither he had been transferred by his superiors in order to study theology.
Whatever may be the truth about these stories, Heraclides seems to have been a versatile and prolific writer on philosophy, mathematics, music, grammar, physics, history and rhetoric. Many of the works attributed to him, however, are probably by one or more persons of the same name.
On his return to Naples he found himself out of touch with the prevailing Cartesianism, and lived quietly until in 1697 he gained the professorship of rhetoric at the university, with a scanty stipend of loo scudi.
Hermagoras devoted himself particularly to the branch of rhetoric known as oixovoyla (inventio), and is said to have invented the doctrine of the four QTavaaS (status) and to have arranged the parts of an oration differently from his predecessors.
Cicero held an unfavourable opinion of his methods, which were approved by Quintilian, although he considers that Hermagoras neglected the practical side of rhetoric for the theoretical.