In the 40s BCE, during his forced retirement from politics under Julius Caesar’s dictatorship, Cicero turned to philosophy, producing a massive and important body of work. As he was acutely aware, this was an unusual undertaking for a Roman statesman because Romans were often hostile to philosophy, perceiving it as foreign and incompatible with fulfilling one’s duty as a citizen. How, then, are we to understand Cicero’s decision to pursue philosophy in the context of the political, intellectual, and cultural life of the late Roman republic? This book takes up this question and makes the case that philosophy for Cicero was not a retreat from politics but a continuation of politics by other means, an alternative way of living a political life and serving the state under newly restricted conditions. The book examines the rhetorical battle that Cicero stages in his philosophical prefaces—a battle between the forces that would oppose or support his project. It presents his philosophy as intimately connected to the new political circumstances and his exclusion from politics. His goal—to benefit the state by providing new moral resources for the Roman elite—was traditional, even if his method of translating Greek philosophical knowledge into Latin and combining Greek sources with Roman heritage was unorthodox. The book provides a new perspective on Cicero’s conception of his philosophical project while also adding to the broader picture of late-Roman political, intellectual, and cultural life.