It had been from the first the custom of some philosophers to adopt this profession, and to expound in the form of rhetorical lectures the principles of their school. In the Flavian period and in the age of the Antonines, this alliance of philosophy, and especially of Stoical philosophy, with rhetoric became more marked, and the foundation of liberally endowed chairs of rhetoric and philosophy by Vespasian, Hadrian, and Marcus Aurelius contributed to sustain it. Discourses of the Platonist Maximus of Tyre, and of the Stoic Dion Chrysostom, have come down to us, and they are both of a high order of intrinsic merit. The first turn chiefly on such subjects as the comparative excellence of active and contemplative life, the pure and noble conceptions of the Divine nature which underlie the fables or allegories of Homer, the dæmon of Socrates, the Platonic notions of the Divinity, the duty of prayer, the end of philosophy, and the ethics of love.(598) Dion Chrysostom, in his orations, expounded the noblest and purest theism, examined the place which images should occupy in worship, advocated humanity to slaves, and was, perhaps, the earliest writer in the Roman Empire who denounced hereditary slavery as illegitimate.(599) His life was very eventful and very noble. He had become famous as a sophist and rhetorician, skilled in the laborious frivolities of the profession. Calamity, however, and the writings of Plato induced him to abandon them and devote himself exclusively to the improvement of mankind. Having defended with a generous rashness a man who had been proscribed by the tyranny of Domitian, he was compelled to fly from Rome in the garb of a beggar; and, carrying with him only a work of Plato and a speech of Demosthenes, he travelled to the most distant frontiers of the empire. He gained his livelihood by the work of his hands, for he refused to receive money for his discourses; but he taught and captivated the Greek colonists who were scattered among the barbarians, and even the barbarians themselves. Upon the assassination of Domitian, when the legions hesitated to give their allegiance to Nerva, the eloquence of Dion Chrysostom overcame their irresolution. By the same eloquence he more than once appeased seditions in Alexandria and the Greek cities of Asia Minor. He preached before Trajan on the duties of royalty, taking a line of Homer for his text. He electrified the vast and polished audience assembled at Athens for the Olympic games as he had before done the rude barbarians of Scythia. Though his taste was by no means untainted by the frivolities of the rhetorician, he was skilled in all the arts that awaken curiosity and attention, and his eloquence commanded the most various audiences in the most distant lands. His special mission, however, was to popularise Stoicism by diffusing its principles through the masses of mankind.(600)