Primary and secondary rhetoric and the study of ancient Chinese rhetoric

Thanks to a citation by John Logan in the winter 2004 Rhetoric Society Quarterly, I'm finally getting around to reading George A. Kennedy's Classical Rhetoric and Its Christian and Secular Tradition from Ancient to Modern Times. Logan cites Kennedy's book as an example (and an influential one, at that) of "the increasingly dominant understanding of the Fifth Century BCE as a predominantly oral culture" and of rhetoric as primarily an oral practice (quotation from Logan's abstract). Kennedy divides rhetoric into "primary rhetoric" and "secondary rhetoric". He described primary rhetoric as follows:

Primary rhetoric is the conception of rhetoric as held by the Greeks when the art was, as they put it, "invented" in the fifth century B.C. Rhetoric was "primarily" an art of persuasion; it was primarily used in civic life; it was primarily oral. Primary rhetoric involves an act of enunciation on a specific occasion; in itself it has no text, though subsequently an enunciation can be treated as a text. (4)

Kennedy describes "secondary rhetoric" as

the apparatus of rhetorical techniques clustering around discourse or art forms when those techniques are not being used for their primary oral purpose. In secondary rhetoric the speech act is not of central importance; that role is taken over by the text. The most frequent manifestations of secondary rhetoric are commonplaces, figures of speech and thought, and tropes in elaborate writing. (5)

I'm excited about this because I've been trying to understand the focus that Xing Lu puts on oral rhetoric in her 1998 Rhetoric in Ancient China, Fifth to Third Century B.C.E.: A Comparison with Classical Greek Rhetoric. Lu, in fact, explicitly rejects commentaries or criticism of written Chinese rhetoric early on in her book, arguing that such studies

are limited in ... their interest in written language at the expense of oral speech. Consequently, such studies offer useful information on Chinese language and stylistic writing but fail to identify theories of rhetoric and communication and to offer specific explanations of the cultural and philosophical orientation[s] that affect rhetorical practice. (27)

Lu doesn't cite Kennedy at this point in her book, but that might not be surprising because of the great influence of Kennedy's book on the study of classical rhetoric in the field of speech communication. It appears, then, that Kennedy's division of primary and secondary rhetorics has jumped from discussions of Greek rhetoric to Lu's study of Chinese rhetoric. I'm currently speculating on how appropriate this jump is. My preliminary conclusion is that it isn't entirely defensible.