The canons of rhetoric refer to the five categories that make up rhetoric as an art form. They are written in ancient Latin texts such as Ad Herennium, written by an unknown author, De Inventione, by the Roman orator and statesman Cicero, and Institutio Oratoria, by Quintilian. These canons are often used as a guide to crafting speeches, as a template for rhetorical education, and as a pattern for discussing and criticizing various forms of discourse. Invention and arrangement are the two canons concerned with the composition of speech, while style, memory, and delivery more directly affect recitation.
Although the principles and practices of the five canons of rhetoric were known by the ancient Greeks, it was not until around 50 BCE that some of the canons were written down by Marcus Tullius Cicero in De Invetione. Later, Marcus Fabius Quintilianus, known as Quintilian, wrote Insitutio Oratoria, which, for the first time in recorded history, put the five canons of rhetoric together. This treatise by Quintilian would go on to inspire Renaissance orators and educators and to revolutionize the way in which rhetoric was practiced and taught.
The five canons of rhetoric begin with the process of invention, from the Latin inventio, meaning to find. Invention is the process that an orator goes through when attempting to develop or refine an argument. It refers to the systematic search for and discovery of arguments using a vast range of methods.
Following the discovery process, the arguments must be arranged. This is the second canon of rhetoric. Arrangement, from the Latin disposition, is the process of ordering the thoughts and arguments discovered during the invention stage. The arrangement of a classical oration usually began with an introduction and then moved on to the statement of fasts, division, proof, refutation, and, finally, conclusion. According to Cicero, arrangement begins with an appeal to ethics, to establish authority, is followed by logical arguments in the next four sections, and concludes with an appeal to the audience's emotions.
Following the first two canons is style are elocution, which determines not what will be said but how the speaker will say it. In the classical era, style was not thought of as simply ornamental. To the ancient Greeks and Romans and the scholars of the Renaissance, style empowered one's ideas, gave them verbal expression, and ensured that the orator's intent was well received.
The fourth canon of rhetoric is memory, or memoria, which refers to more than simple mnemonic aids and devices. The author of the Ad Herennium asserts that memory is linked to the first canon, invention. This implies that the speaker must store up the information and arguments discovered during the invention process for later use. Memory concerns itself with the improvisational necessities of public speaking and the psychological demand on the orator, allowing the rhetor to think quickly and clearly.
Delivery, from the Latin action, is much like style, in that it is concerned with how an argument is said and not so much with what is being said. A successful delivery of a speech is the result of intense vocal training and incorporates body language and gestures. Delivery makes an intensely powerful appeal to pathos, or the emotions of the audience, and as such, is crucial in the rhetorical process.