The relative as well as absolute aggrandizement of the executive branch of the national government is the outstanding single fact in the political experience of the United States. The Presidency today is not only stronger in relation to Congress and the Supreme Court but its role in the whole life of the nation has become much larger than apparently envisaged by the Founders. This development, however, is not considered a departure from the original scheme of government because the Constitution is held to be a “living document.” The intermittent but cumulative growth of the Presidency has been absorbed into current constitutional theory on the general principle laid down by Justice Holmes deciding a question of federal-state relations: “This case before us must be considered in the light of our whole experience and not merely in that of what was said a hundred years ago.” This unity of theory and practice constitutes, indeed, the genius of American politics to which Professor Daniel Boorstin has applied the term “givenness.” The two components of this “givenness,” according to Professor Boorstin, are the idea of a preformed original theory given to the nation by the Founding Fathers and adequate to all its future needs, and the idea of an implicit theory forever embodied in American institutions. Combined, these two tenets produce a sense of continuity — “homogeneity,” “seamless web” — in which past and present, tradition and progress, constitutional law and political practice, are blended into that peculiar American optimism, at once reverent and practical. Since the Presidency participates in this “givenness,” it also constitutes an indestructible composite of constitutional interpretation and history. It is a “living institution.”