The Introduction presents the main questions and aims of the book. I argue that Roman thinkers used the metaphor of the body politic to articulate competing visions of the res publica between the Catilinarian Conspiracy and Year of the Four Emperors. I frame my discussion in relation to the Cambridge School of intellectual history, which has catalyzed the revival of interest in classical republicanism. In contrast to its focus on questions of liberty and popular sovereignty, my book turns towards problems of statesmanship and constitutional transformation. It asks how a foundational metaphor of civic organization evolved in response to the establishment of autocracy. It foregrounds the importance of metaphor as an avenue of political thought.