My father came to this country from Scotland via England. He knew beforehand that the citizenship ceremony here would be a significant event. Even so, he wasn’t prepared for the emotional power it had for him. He became a citizen in a group like this, neither very large nor very small. Everyone in his batch of new citizens was moved, my father included, but they were all overwhelmed by each other, new members of a centuries-old tide of migration here to the “empire of liberty.”

Something like that, both momentous and every-day, is afoot here. Brand new Americans are being made. We are all lucky: the old citizens in what we got for free, and the new ones, in knowing what it’s worth. We have a lot to tell one another. The conversation begins now.

Monticello is a beautiful spot for this event, full as it is of the spirit that animated this country’s foundation: boldness, vision, improvisation, practicality, inventiveness and imagination, the kind of cheekiness that only comes with free-thinking and faith in an individual’s ability to change the face of the world. It’s easy to imagine Jefferson saying to himself, “So what if I’ve never designed a building before? If I want to, I will.” With its slave quarters a part of its history, it’s also a healthy reminder that our old country, your new country, for all its glory, has always had feet of clay, and work that needed doing. So it’s good that you’ve come, fresh troops and reinforcement. We old citizens could use some help. Welcome. We need you. There’s much to be done.

“We hold these truths to be self-evident, that all men are created equal.” Jefferson’s words are so familiar, so potent, so important, so grand and fine, it’s hard to believe that any single person actually picked up a pen, dipped it in ink, and, on a blank white sheet, made appear for the first time what had never before existed in the whole history of the world. By scratching away at the page, he called a country into being, knowing as he wrote that it was no more than an idea, that might, at any instant, be erased and destroyed, with the United States of America becoming just another sorry footnote in the history of suppressed rebellions against tyranny. You can’t help but be impressed by all which that one person, and the small group of individuals around him, not much larger than your group of new citizens, won for so many.

Abraham Lincoln called ours “government of the people, by the people, for the people.” I claim that the word “people” stands for a great many individuals, rather than for a collective. It wasn’t a mob, but individuals acting in a group that made this country up out of whole cloth. These are just the sort of people the country needs now, individuals acting together for the common good. Theodore Roosevelt said, “The foundation stone of national life is, and ever must be, the high individual character of the average citizen.” That understates the case: the United States — a participatory democracy is one way political scientists describe it — counts on its citizens turning out to be above average, like all the students in Lake Woebegone.

That’s where you come in. Thomas Jefferson’s fragile idea looks pretty solid now. But for all the building and bulldozing, the wealth and resources, the United States is still a contract among individuals around an idea. If the saying is, “contracts are made to be broken,” we want this one to hold, which requires all hands to be on deck.

The United States may seem like a fixed star, but it isn’t. It is a relationship between citizens and an idea, and, like all relationships, it changes with the people in it. Its past is always up for reargument; its present is constantly unfolding, complex, a continuum of surprises, and the future is yet to be written.

We all need to exercise our lungs in the discussion: what does our past mean, what are we to do now, and what will be our future? This is not a job just for TV talking heads and politicians. Nor for moneyed interests, nor for single-issue movements. As the World War I recruiting poster said, “Uncle Sam needs you.” Needs us. We are greatly mistaken to think sharing our views with the television set or our husbands and wives, and voting occasionally, is enough. Don’t you who are new pick up these bad habits from us.

History shows that America is the all-time greatest self-correcting nation. We have been marvelously able to correct our course in the past because the founding idea — individual freedom expressed through direct representation — has stirred its citizens to participate and interfere. Information from the people makes the government smarter. Insufficient information from us makes it dumber. Or, as Abraham Lincoln more elegantly expressed it, “Why should there not be a patient confidence in the ultimate justice of the people? Is there any better or equal hope in the world?”

The old model of our citizenly relation to politics was of a group of people under a tree, taking turns on the stump all day, discussing the issues of the time. Then came the town meeting, where every citizen can have his say. Old citizens like me hope that between you and the Internet, the old model will get a new lease on life.

Citizenship isn’t just a great privilege and opportunity, though it is all that. It’s also a job. But don’t worry: it’s a great job. Everything that happens within this country politically, and everywhere in the world its influence is felt, falls within its province. You’ll never be able to complain about being bored at work. As we multiply our individual voices, we multiply the chances for our country’s success.

I hope you won’t waste all the time I have in figuring out how a citizen should relate to his government. Talk to it. Tell it what you like. Tell it what you don’t like. Vote, of course. Think about what you want our future to look like. Let the government know. Roll up your sleeves, stick out your chin, sharpen your elbows, get in the middle of things, make them different. You are bound to get a lot of things wrong. That’s what we do. But the possibility of error is no excuse for being quiet, and I say this on good authority. As Theodore Roosevelt put it, “Man was never intended to become an oyster.”

Whether you work within the Democratic or Republican parties, or join in supporting a bi-partisan ticket for 2008, as I have, in an effort to drive the parties to work together and to show them how it’s done, don’t be discouraged by the odds. It isn’t all determinism and the tide of history. An individual can upend what seems determined, and speed or reverse the tide. The man on whose estate we stand, by pushing his pen across a blank page, proved that.

Mr. Waterston, an actor, is the national spokesman for Unity08. This column is excerpted from his July 4 remarks at a swearing-in ceremony for new citizens at Jefferson’s Monticello.