Having posited this thesis in 1756, Sheridan was reiterating it still in the material prefatory to his pronouncing dictionary in 1780, and he never rested with publication alone. As early as 1757 he lectured on the principles of education, and he first presented his course of lectures on elocution in 1758-59 at Oxford and Cambridge. Over the years the course proved to be both popular and financially rewarding, and Sheridan sometimes presented the lectures in order to relieve financial embarassment. Nevertheless, his devotion to the cause was the crucial factor. His interest in language somehow became an almost blind devotion to spoken English, and through his course he could carry his message to influential audiences in England, Ireland, and Scotland; the Edinburgh Select Society sponsored two series in 1761, and Sheridan was lecturing on elocution as late as 1785. The _Discourse_ typifies Sheridan's simplistic interpretation and the evangelistic ardor with which he addressed his audiences. He was not content to fault an overemphasis in the study of Latin, nor was he satisfied to argue that "the support of our establishments, both ecclesiastical and civil" rests upon public discussion. Many in his audiences would have agreed, and few would have taken issue with the contention that the "art of elocution" needed further cultivation. But Sheridan pressed on to insist that the written language, being an invention of man, "can have no natural power," and he argued that the "highest delights" of aesthetic pleasures must wait upon the perfection of spoken English. He even went so far as to suggest that the study of "grammar, rhetorick, and oratory" explained the outstanding artistic achievements of Greece and Rome. Moreover, "other benefits to society" would add to "the glory of the nation" and to the "ornament of individuals, and of the state in general" through a loosing of silent tongues. Sheridan dreamed that the study of elocution, with a voice "far sweeter than the syren's song," would so entrance young students that they would linger long in native academic groves, avoiding the baneful influence of travel abroad "at the most unfit and dangerous season of life." Thus, individual and social perfection had to be predicated upon the study of spoken English, and Sheridan implied that to slight this study was to offer an affront to the divine plan for earthly progress.