As defined by the Roman philosopher Cicero and the unknown author of Rhetorica ad Herennium, the canons of rhetoric are these five overlapping divisions of the rhetorical process:
- Invention (Latin, inventio; Greek, heuresis)
Invention is the art of finding the appropriate arguments in any rhetorical situation. In his early treatise De Inventione (c. 84 B.C.), Cicero defined invention as the "discovery of valid or seemingly valid arguments to render one's cause probable." In contemporary rhetoric, invention generally refers to a wide variety of research methods and discovery strategies.
- Arrangement (Latin, dispositio; Greek, taxis)
Arrangement refers to the parts of a speech or, more broadly, the structure of a text. In classical rhetoric, students were taught the distinctive parts of an oration. Though scholars did not always agree on the number of parts, Cicero and Quintilian identified these six: the exordium (or introduction), the narrative, the partition (or division), the confirmation, the refutation, and the peroration (or conclusion).
- Style (Latin, elocutio; Greek, lexis)
Style is the way in which something is spoken, written, or performed. Narrowly interpreted, style refers to word use, sentence structures, and figures of speech. More broadly, style is considered a manifestation of the person speaking or writing. Quintilian identified three levels of style, each suited to one of the three primary functions of rhetoric: the plain style for instructing an audience, the middle style for moving an audience, and the high style for pleasing an audience.
- Memory (Latin, memoria; Greek, mneme)
Memory includes the methods and devices (including figures of speech) used to aid and improve the memory. Roman rhetoricians made a distinction between natural memory (an innate ability) and artificial memory (particular techniques that enhanced natural abilities).
- Delivery (Latin, pronuntiato and actio; Greek, hypocrisis)
Delivery refers to the management of voice and gestures in oral discourse. Delivery, Cicero said in De Oratore, "has the sole and supreme power in oratory; without it, a speaker of the highest mental capacity can be held in no esteem; while one of moderate abilities, with this qualification, may surpass even those of the highest talent."