In 'Politics' Book III, Aristotle defines a constitution as an ‘order’ (taxis) of ‘offices’ (haiarchai). A constitution is an organization that transmutes what would otherwise be sheer power into the lineaments of authority. What makes power constitutional is its delineation in terms of offices – their legal capacities, their terms, their mode of selection, and the control exercised over them. Conversely, the ancient Greeks recorded a vacancy of office as a year of 'anarchia'. By exploring eleven episodes of 'anarchia' or anarchy in the eleven centuries of history of ancient Athenian 'archons' (holders of a particular office), this lecture sheds light on the nature of political office and what we today might think of as its legitimacy.