This statement, often attributed to the 17th-century English political theorist James Harrington, particularly from his work "The Commonwealth of Oceana" (1656), encapsulates a core republican idea about the relationship between property, power, and liberty. It argues that the distribution of economic resources, specifically land ('estates'), is fundamental to the distribution of political power, and that a balanced distribution of power is essential for true liberty.

Harrington's central argument was that the 'balance of property' determines the 'balance of power.' He observed that whoever holds the majority of property in a society will inevitably hold the majority of political power. If land is concentrated in the hands of a few (e.g., a monarchy or aristocracy), then political power will likewise be concentrated, leading to an oligarchy or tyranny. Conversely, if property, especially land, is widely distributed among the citizenry, it creates an 'equality of estates.'

This 'equality of estates' then leads to an 'equality of power.' When many citizens own property, they have a vested interest in the political system and possess the economic independence necessary to participate in governance without being beholden to a powerful few. This diffusion of property prevents any single group from accumulating excessive power and dominating others.

Finally, Harrington asserted that 'equality of power is liberty.' For him, liberty was not merely freedom from arbitrary rule, but the active capacity of citizens to participate in self-governance and to live under laws they have consented to. A balanced distribution of power, stemming from a balanced distribution of property, ensures that no one group can oppress another, and that citizens are free because they are self-governing. It implies a republican ideal where civic virtue and public participation are fostered by economic independence and a shared stake in the commonwealth.

In contemporary terms, Harrington's insight remains relevant in debates about economic inequality and its impact on democratic health. Many argue that extreme wealth concentration can translate into disproportionate political influence, undermining the principle of equal political power and thus, ultimately, liberty. The quote highlights the enduring belief that a healthy republic requires a broad distribution of both economic resources and political agency to safeguard freedom.