My girlfriend is smarter than me. So you can imagine why it can sometimes be frustrating to debate her. But this summer as we sat in front of Mount Rushmore, someone made my argument for me.

I had insisted on stopping by that great monument to some of our greatest citizens, and beneath the four faces we started talking about American history. As I marveled at the monument, my girlfriend pointed out that this was only a part of our nation’s history. She questioned whether four white men, all long dead, could be truly representative of a country as diverse as ours.

I argued that those men are. They are truly representative because they, despite being limited by their age, spoke of essential American truths—like open discourse, generosity, and a commitment to freedom. As I said this, a man tapped me on the shoulder. He was a middle-aged Indian man, and asked me if I would take a picture of him and his family in front of Mount Rushmore. I said of course and took a picture of nine people, representing three generations, all smiling in front of the four stone-faced men.

But I may have been wrong to feel vindicated by my picture-taking. It is easy for me to feel comfortable in the American tradition. After all, my ancestors were never outside of it. I’ve never needed to squeeze or shed any part of my personal heritage to feel entitled to that national heritage. I should not be so bold to think that simply because I have been comfortable, we can all be at ease.

Two of those men owned African slaves. Another threw men in jail without benefit of charge or trial. Another created the Panama Canal at the barrel of a gun.

So I would concede to my more intelligent girlfriend that she’s right: These men cannot represent all of America. But they, like all of us, are part of one heritage—namely a belief in liberty and justice for all. And it is that sentiment, first articulated in the Declaration of Independence, that is the birthright of every American, whether they are first generation or fifth.

If only I had remembered the speech Lincoln gave in Chicago in 1858. Lincoln was defending the idea that all of us are connected to the ideals first enunciated in our Declaration of Independence from Great Britain. He talked about the old men of 1776, and how many of us could not claim them as direct ancestors.

He spoke of all the men “who have come from Europe themselves or whose ancestors have come hither and settled here, finding themselves our equals in all things. If they look back through this history to trace their connection with those days by blood, they find they have none, they cannot carry themselves back into that glorious epoch and make themselves feel that they are part of us, but when they look through that old Declaration of Independence they find that those old men say that ‘We hold these truths to be self-evident, that all men are created equal,’ and then they feel that that moral sentiment taught in that day evidences their relation to those men, that it is the father of all moral principle in them, and that they have a right to claim it as though they were blood of the blood, and flesh of the flesh of the men who wrote that Declaration, and so they are.”

Our charge is that we never forget that each person who has come to America is blood of the blood and flesh of the flesh of the men who wrote the Declaration. For as Lincoln put it in Chicago, “That is the electric cord in that Declaration that links the hearts of patriotic and liberty-loving men together, that will link those patriotic hearts as long as the love of freedom exists in the minds of men throughout the world.”