After centuries of a chameleon-like existence, the complete Ciceronian rhetoric emerged in England just in time to meet a savage onslaught from the methods of science and the new epistemology.[8] Eventually, rhetoricians such as Campbell and Blair were to successfully blend the old and the new, but the elocutionists found fertile ground in delivery alone. They began, as Sheridan did, with the testimony of Cicero and Quintilian because _actio_, or _pronuntiatio_, was one of the five established canons of classical rhetoric. A favorite citation, though Sheridan did not use it, was Demosthenes' reputed response when asked to name the three most important parts of rhetoric: "Actio, actio, actio." The endorsement of antiquity lent powerful support to the study of delivery, and this was the one canon that had not been subjected to regular exhaustive analyses throughout the rhetorical tradition. Here was a topic ripe for further investigation, and by Sheridan's day, the tones, looks, and gestures of delivery had achieved commonplace status in discussions of man's emotions.
Sheridan spoke as if this natural language of the passions were "hardly ever thought of," but the belief that tones, looks, and gestures were external signs of internal emotions was firmly established by the middle of the eighteenth century. The notion has received some attention throughout western thought, but most speculation appears to date from Descartes' _Les Passions de l'ame_ in 1650. The increasing concern with mind-body problems encouraged inquiries into the nature and function of the natural language in all areas relating directly to man's emotion and its expression. The topics were as various as religion and physiognomy, but discussions of the natural language construct centered upon human communication, particularly in the arts.
The construct became especially significant in analyses of painting and sculpture. Examples of its impress can be seen in Le Brun's sketches of the passions,[9] in Hogarth's having embraced "the commonly received opinion, that the face is the index of the mind,"[10] and in Dryden's contention that "to express the passions which are seated in the heart, by outward signs, is one great precept of the painters." Dryden added that "in poetry, the same passions and motions of the mind are to be expressed,"[11] and the natural language found its way into most discussions of tragedy and the epic. Other examples of literary analysis in which the construct operated include Steele's _Prosodia Rationalis_, Say's _An Essay on Harmony, Variety, and Power of Numbers_, and Kames' _Elements of Criticism_. In sum, it was almost universally accepted that the creative artist was to observe and record the natural language of the passions. In Sheridan's words, he was to perceive and delineate the "operations, affections, and energies, of the mind itself ... manifested and communicated in speech."