Chapter 3 focuses on liberty and servitude, and the way in which these conditions – defined in Roman law in terms of the status of individual persons – are predicated of collective bodies described as civitates and populi in Roman political philosophy. Machiavelli’s relationship to this particular conception of liberty has been at the centre of much recent literature on classical, early modern, and contemporary republicanism, but his theory of freedom requires closer scrutiny, not least because of its relationship to a line of thinking about popular self-government which had been used by humanists to articulate a theory of popular sovereignty from the late fourteenth to the early sixteenth century in Renaissance Florence. This chapter shows how the key concepts of this thesis come from Cicero’s philosophy, which conveys to the humanists an influential account of how to constitute the entity which he calls the populus as the ultimate bearer of public authority. Cicero’s view of ‘the people’ as the master of its own affairs informs his definition of the res publica as res populi – literally, a ‘thing of the people’ – and this chapter shows how it informs the very basis of the classical republican tradition which Machiavelli inherits and reworks.