In book I of De re publica Cicero famously defined the res publica as res populi, the business or the interest of the people, and then went on to flesh out what we should understand to constitute a people: ‘a collection of a great number of human beings, joined in partnership through agreement or unanimity of law or justice or right (iuris consensu) and through sharing in advantage (utilitatis communione)’. ‘Sharing in advantage’ seems clear enough. But my disjunctive rendering of iuris consensu, with its repeated ‘or’ and unconvincing ‘of’, is intended to give an indication of the difficulty translators and other interpreters have had in grasping what Cicero meant by the expression. This chapter offers a fresh attempt at the problem.