QUOTE : The main signpost that helps political realism to find its way through the landscape of international politics is the concept of interest defined in terms of power. This concept provides the link between reason trying to understand international politics and the facts to be understood. It sets politics as an autonomous sphere of action and understanding apart from other spheres, such as economics (understood in terms of interest defined as wealth), ethics, aesthetics, or religion. Without such a concept a theory of politics, international or domestic, would be altogether impossible, for without it we could not distinguish between political and nonpolitical facts, nor could we bring at least a measure of systematic order to the political sphere.<br />We assume that statesmen think and act in terms of interest defined as power, and the evidence of history bears that assumption out. That assumption allows us to retrace and anticipate, as it were, the steps a statesman - past, present, or future - has taken or will take on the political scene. We look over his shoulder when he writes his dispatches; we listen in on his conversation with other statesmen; we read and anticipate his very thoughts. Thinking in terms of interest defined as power, we think as he does, and as disinterested observers we understand his thoughts and actions perhaps better than he, the actor on the political scene, does himself.<br />The concept of interest defined as power imposes intellectual discipline upon the observer, infuses rational order into the subject matter of politics, and thus makes the theoretical understanding of politics possible. On the side of the actor, it provides for rational discipline in action and creates that astounding continuity in foreign policy which makes American, British, or Russian foreign policy appear as an intelligible, rational continuum, by and large consistent within itself, regardless of the different motives, preferences, and intellectual and moral qualities of successive statesmen.