The expressionist theory of rhetoric, as presented in critical passages of selected eighteenth century texts, is examined in this essay. The introductory section of the essay discusses historical attitudes toward the relationship between grammar, logic, and rhetoric and points to the emergence and wide acceptance during the eighteenth century of expressive theories of art that justified the union of rhetoric with the fine arts. Subsequent sections examine passages from eighteenth century texts in the context of assumptions of the intellectual community of that century concerning the following areas: the interaction of mind and body; the significance of nonverbal communication, or "natural signs," in the expression of emotion; and the way in which the quality of verbal and nonverbal forms of expression affects the emotional reactions of an audience. The essay concludes by noting that the treatment of the classical rhetorical canons during the closing decades of the eighteenth century was fully consistent with the expressionist attitude and by telling how rhetoric rapidly became an object of opprobrium during the nineteenth century as the assumptions supporting the expressionist theory lost their popularity. (GT)