“All through our history, our presidents and leaders have spoken of national unity and warned us that the real obstacle to moving forward the boundaries of freedom, and the only permanent danger to the hope that is America, comes from within,” President Ronald Reagan said in a July 4, 1986, address to the nation. “It’s easy enough to dismiss this as a kind of familiar exhortation. Yet the truth is that even two of our greatest Founding Fathers, John Adams and Thomas Jefferson, once learned this lesson late in life.”

President Reagan noted that after the American government was formed, “something called partisan politics began to get in the way. After a bitter and divisive campaign, Jefferson defeated Adams for the presidency in 1800. And the night before Jefferson’s inauguration, Adams slipped away to Boston, disappointed, brokenhearted and bitter.”

But the two men later reconnected through an extraordinary correspondence, not just about the issues of the day, but more importantly, as President Reagan noted, about “gardening, horseback riding, even sneezing as a cure for hiccups. But other subjects as well: the loss of loved ones, the mystery of grief and sorrow, the importance of religion and of course the last thoughts, the final hopes of two old men, two great patriarchs, for the country that they had helped to found and loved so deeply.”

Jefferson and Adams made their way back to each other as people, not as political rivals. “It was their last gift to us, this lesson in brotherhood, in tolerance for each other,” President Reagan said.

We should never forget that parting gift they gave us, and remember how partisan politics has built a wall of anger and recrimination. These two Founding Fathers came back to each other, by seeing once again the humanity within each other — from sneezing and hiccups to “the mystery of grief and sorrow.”

We try to, and often do, live up to the elevated sentiments immortalized in Jefferson’s Declaration of Independence. But not always. The belief in those self-evident truths is precisely what makes America great — but we’re not perfect and neither is our nation. A commitment has to be made by every generation to keep moving the boundaries of freedom forward.

“The nature of injustice is that we may not always see it in our own times,” retired Supreme Court Justice Anthony Kennedy said. “The generations that wrote and ratified the Bill of Rights and the Fourteenth Amendment did not presume to know the extent of freedom in all its dimensions, and so they entrusted to future generations a charter protecting the right of all persons to enjoy liberty as we learn its meaning.”

To sanctify the men of 1776 is not only foolish, but dangerous. Many of them held their fellow human beings in slavery.

The true gift the Founders gave us, as Justice Kennedy said, is a template to define and enshrine American ideals for the future. Happy Independence Day.