Until the modern era there was no single international system, but rat — Robert Gilpin

"The parallel existence and mutual interaction of "state" and "market" in the modern world create "political economy"; without both state and market there could be no political economy."

"A precondition for political change lies in the disjuncture between the existing social system and the redistribution of power toward those actors who would benefit most from a change in the system."

"Powerful groups set constraints on and may even determine the actions of state authority. They constitute the society that is protected by the state; their particular concept of justice reigns. The definition and functioning of property rights tend to advance their interest and welfare. ...the basic domestic function of the state is to define and protect property rights of individuals and groups. ...The primary external function of the state is to protect the property rights and personal security of its members vis-à-vis the citizens and actions of other states."

"The relative stability of the system is... largely determined by its capacity to adjust to the demands of the actors affected by changing political and environmental conditions."

"Ultimately...the hierarchy of prestige in an international system rests on economic and military power."

"[In] the definition of international system... There is some "form of control" that regulates behavior and may range from informal rules of the system to formal institutions. ...A view prevalent among many scholars of political science is that the essence of international relations is precisely the absence of control... a condition of anarchy..."