John Q. Adams on Foreign Policy and War

July 4, 1821, from an address delivered by Secretary of State John Quincy Adams
America, in the assembly of nations, since her admission among them, has invariably, though often fruitlessly, held forth to them the hand of honest friendship, of equal freedom, of generous reciprocity. She has uniformly spoken among them, though often to heedless and often to disdainful ears, the language of equal liberty, equal justice, and equal rights. She has, in the lapse of nearly half a century, without a single exception, respected the independence of other nations, while asserting and maintaining her own. She has abstained from interference in the concerns of others, even when the conflict has been for principles to which she clings, as to the last vital drop that visits the heart. She has seen that probably for centuries to come, all the contests of that Aceldama, the European World, will be contests between inveterate power, and emerging right.

Wherever the standard of freedom and independence has been or shall be unfurled, there will her heart, her benedictions and her prayers be. But she goes not abroad in search of monsters to destroy. She is the well-wisher to the freedom and independence of all. She is the champion and vindicator only of her own. She will recommend the general cause, by the countenance of her voice, and the benignant sympathy of her example.

She well knows that by once enlisting under other banners than her own, were they even the banners of foreign independence, she would involve herself, beyond the power of extrication, in all the wars of interest and intrigue, of individual avarice, envy, and ambition, which assume the colors and usurp the standard of freedom. The fundamental maxims of her policy would insensibly change from liberty to force. The frontlet upon her brows would no longer beam with the ineffable splendor of freedom and independence; but in its stead would soon be substituted an imperial diadem, flashing in false and tarnished lustre the murky radiance of dominion and power. She might become the dictatress of the world: she would be no longer the ruler of her own spirit.

...

Her glory is not dominion, but liberty. Her march is the march of mind. She has a spear and a shield; but the motto upon her shield is Freedom, Independence, Peace. This has been her declaration: this has been, as far as her necessary intercourse with the rest of mankind would permit, her practice.

Why it's interesting
America's modern role as a sort of police department for the world seems to contradict the early beliefs established by the founding fathers. For more on the cultural shift from a militarily isolationist view to a more belligerent view, see Jingoism on wikipedia. For George Washington's take, see George Washington on Foreign Policy on this wiki.