August 25 marks the 50th anniversary of the 1963 March on Washington. Martin Luther King Jr.‘s speech at that great rally is rightly honored as one of the greatest speeches in American history. All Americans recognize the soaring rhetoric of the final portion of the speech, where King speaks of a dream of an America without legal discrimination or racial prejudice. But the first part of that speech, wherein King speaks of the Declaration of Independence and Constitution, is not as well-known but deserves to be. That portion demonstrates King’s commitment to the conception of justice held at the American founding.

In the third paragraph of King’s text, he says that “when the architects of our Great Republic wrote the magnificent words of the Constitution and the Declaration of Independence, they were signing a promissory note to which every American was to fall heir.” With this reference to the declaration, there is a clear echo of that other great American speech from 100 years before King’s March on Washington speech: Lincoln’s Gettysburg address, which speaks of America as “dedicated to the proposition that all men are created equal.”

A “promissory note” is not one of those terms we use frequently, but it’s a powerful term. It’s not a hope or a wish. In fact, there was an international agreement in 1930 which defined a promissory note as implying an unconditional promise. For King, the Declaration of Independence, which he quoted directly from, was a promissory note that the United States would ultimately guarantee for all people “the unalienable rights of life, liberty, and the pursuit of happiness.” As King then said, “It is obvious that America has defaulted on this promissory note.” King was not calling for the destruction of the American political order, but rather for us to be true to the ideals of the founding, and that’s why it is important that he quoted the Declaration.

It is more than reasonable to assume that King could have been so disheartened by the treatment of blacks in the United States that he would have rejected the proposition that the United States had the capacity to correct past wrongs and ultimately be true to the Declaration’s claim about the equality of rights for all people. Instead, he said that “we refuse to believe that the bank of justice is bankrupt.” It is interesting to contrast this with someone like Howard Zinn, author of “The People’s History of the United States,” a widely assigned textbook that portrays oppression as central and unending in American history, who seemed to believe that America had no capacity for respect for rights and could never improve. King added that “we refuse to believe that there are insufficient funds in the great vaults of opportunity in this nation.” For nearly all individuals, it doesn’t take more than one or two unfulfilled promises made by another to result in giving up on the possibility of working with that person or group. Despite the unfulfilled promise of the protection of rights and the protection of freedom, King hadn’t given up on America.

Finally, at the end of King’s speech is a beautiful sequence where he presents images of a truly post-racial society – and there again is one more reference to the Declaration of Independence. As he begins this “dream” section, he says: “I still have a dream. It is deeply rooted in the American dream. I have a dream that one day this nation will rise up, live out the true meaning of its creed: We hold these truths to be self-evident, that all men are created equal.”

King’s hopes were rooted in that powerful second paragraph of the Declaration of Independence that claims that no man by nature is ruler or the servant of another. It’s not just a great statement during a social struggle, it’s a great statement about what it means to be an American.