Wilson, Douglas, and Nathan D. Wilson. The Rhetoric Companion: A Student's Guide to Power in Persuasion. Moscow, Idaho: Canon, 2011.
Lesson 4, “Invention: The First of the Five Canons.” pp. 29-32
Wilson lists the five canons of rhetoric, citing Rhetorica Ad Herennium on the margin of p. 29 - “Invention, Arrangement, Style, Memory, and Delivery.” Invention is the beginning of the process. Wilson goes on to say that “Another method of arranging the study of rhetoric is according to the different parts of the discourse - exordium, narration, proofs, peroration, and so on” (Wilson 2011, 29). Invention is deriving the content of communication. This includes propositions and proofs. Wilson continues on p. 30 to discuss the three types of proofs identified by Aristotle, given their Greek names of ethos, pathos, and logos. The “ethical proof depends upon the character of the speaker; pathetic proof depends upon and appeal to the emotions of the audience; logical proof depends upon the issues contained within the argument” (Wilson 2011, 30). Wilson observes briefly that although we are usually uncomfortable with ethos and pathos we use them frequently.
In the process of invention we must also consider what the point of the discussion is. All the material we gather must be pertinent. This requires the speaker to be sensitive to his identity, that of the audience, and both the speaker’s and audience’s impression of each other and of the topic.