Definition
Marcus Tullius Cicero (106-43 BCE) was a Roman statesman, advocate, and theorist who is the most important single figure in the Western rhetorical tradition after Aristotle. He combined an extraordinary practical career — consul, defender of the late Republic, prolific courtroom orator — with sustained theoretical work, leaving behind a body of speeches and treatises that became the curriculum of rhetorical education for nearly two thousand years.
His principal theoretical works are De Inventione (a youthful handbook), De Oratore (a mature dialogue on the ideal orator), Brutus (a history of Roman oratory), and Orator (on style). With the anonymous Rhetorica ad Herennium — once attributed to Cicero, now thought independent but contemporary — these texts codified the five canons (invention, arrangement, style, memory, delivery), the three styles (plain, middle, grand), the three branches inherited from Aristotle, and the doctrine of the ideal orator as the broadly educated vir bonus dicendi peritus — a good man skilled in speaking.
Why it matters
How it works
Cicero's theoretical move is to insist that rhetoric is not a narrow technical discipline but the capstone of a complete education. The ideal orator must know philosophy, law, history, and the affairs of the day; technical mastery of the canons alone produces a fluent fool. De Oratore stages this argument through fictional dialogue between leading Roman orators, capturing the social practice of rhetoric as well as its theory.
In practice, Cicero left more usable inheritance than any other ancient writer. His speeches modelled the genres; his treatises supplied the vocabulary; his prose set the standard for Latin style that every educated European tried to imitate from the Carolingian renaissance through the 19th century. To learn rhetoric in the West, until very recently, was to learn Cicero.