To answer that question this analysis examines the work of the political realist thinker Hans J. Morgenthau who transformed the study of international relations with his analysis of this question. As this analysis turns to Morgenthau, a founder of the National Committee and the chief theorist of the national interest, to define the complexities of the term, Morgenthau read the writings of the founders of America-the Federalists-for an explication of what has become the most important term in the lexicon of international relations. As relayed in this analysis, Morgenthau distilled three precepts underlying the founders' conception of America's interest in foreign affairs and nine rules that govern the art of diplomacy. They are identified and explained here in an analysis that shows, among other things, the durability of Morgenthau's thought.