Our study focuses on Cicero's discourse through his theoretical works on rhetoric ( Brutus, Orator and Oratore) and his practical speeches as a politician and lawyer ( In Verrem I, In Catilinam I, Pro Archia, Pro Flacco and Pro Milone). We have developed two main themes:the principles of rhetoric in general and those of Cicero in particular, and a detailed analysis of his practical speeches cited above, with the sole aim of reconciling theory and practice.