Ettlich, Ernest Earl.  “Theories of Invention in Late Nineteenth Century American Rhetoric.”  Western Speech Journal 30 (1966):  233-241.

• E. notes that the topic of rhetorical invention has long been problematic/contested.  E. observes that Ramus’ revision of the liberal arts curriculum during the 1500s was the most serious challenge to rhetorical invention (classically conceived) before the 19^th century.  Ramus assumed that invention and arrangement belonged to dialectic and considered only style and delivery as rhetorical (233).
• E. notes that some folks during the 19^th century still considered invention in the classical sense (Quackenbos, John Hart, Brainerd Kellogg).  Others expanded invention to include arrangement as well (Henry Day, John Franklin Genung).  This conception of invention has its roots in the Rhetorica ad Herennium.  In this text arrangement is given its own space for “the ordering and distribution of the matter making clear the place to which each thing is to be assigned”; however, his introduction of the parts of discourse are occur in the section on invention (Book I, Chapter iii, Section 4).
• E. highlights how Cicero simplified the 5-canon system into a three division system that merged invention and arrangement.  For Cicero, rhetoric can be divided into matter, language, and memory (Book I, Section 3 in De Partitione Oratoria).  Quintilian expands on Cicero’s divisions by noting that, “aftern an initial division of oratory into invention and expression, he [Cicero] assigns matter and arrangement to invention, words and delivery to expression and makes memory a fifth department common to them all and acting as their guardian” (Institutio Oratoria Book III, Chapter iii, Section 7).
• Rhetoric was divided in the 19^th century into invention and style: rhetoric was based on the sciences of logic and grammar while style was divided into diction (choice of words) and composition (combinations of words into phrases, sentences, and paragraphs); invention was divided into the discovery of ideas and organization of those ideas (236).  In this sense, the division of rhetoric into invention and style could be seen as a division of words (style: the combination of words into larger units) and ideas (invention: the choice of ideas and the comibination of those ideas into larger units).
• E. highlights a further three-part division concerning invention in the 19^th century academy: those that advocated for it and taught it, those that advocated for it but didn’t teach it (via Blair who noted that “I am afraid it is beyond the power of art to give any real assistance to invention”), and those that didn’t consider it a proper division of rhetoric (rhetoric is only concerned with the way to say something, not finding something to say – that’s logic’s job) (237).