I believe in American Exceptionalism, the idea that America is a unique nation with a special mission. This does not mean that America is “better” than other places, nor that other peoples don’t have their own exceptional stories. But even before the first European settlers had disembarked on the New England coast, America was as much an idea as a place, and it was a land were people came – among other reasons – to work out their destinies. As Americans continually fell short of their ideals, someone would arise, like a biblical prophet, to call us back to our principles. In particular, four men – writing across more than 300 years of history – remind us of America’s destiny to be a beacon to the world.

• In his 1630 sermon, “A Model of Christian Charity,” John Winthrop urged his small band of Puritans to “be as a city upon a hill,” for they would be judged – by themselves and by the world – on the principles they had come to live by.

• In 1776,Thomas Jefferson looked out on an America that had become a sprawling and diverse land; and whereas Winthrop had stressed community (“we must be knit together, in this work, as one man”), Jefferson wrote that individual equality and liberty must be the foundation of the new nation.

• Eighty-three years later, Abraham Lincoln warned his audience at Gettysburg that the ideals of the Declaration were threatened by war and undermined by slavery.

• And in 1963, at the base of the Lincoln Memorial, Martin Luther King, Jr. referred directly to the earlier documents to call Americans back to the national ideals we espoused but did not live by.

As we remember America’s founding, it is well, also, to remember the enduring tension between America’s ideals and America’s reality.