Together with the histories of Polybius and Livy, Cicero's polemical speeches and writings, and his personal correspondence, form some of the most important historical resources for understanding the Roman legal and political system. Here we focus only on his political theory narrowly construed, part of his program to adapt Greek philosophy to Roman social and political purposes, bypassing even the extended defense of the role of oratory in political life that became something like a handbook for the study of rhetoric.

On Politics: A History of Political Thought: From Herodotus to the Present (2012) - Ch. 4 : Roman Insights: Polybius and Cicero