The melting pot, self-reliance and shining city on a hill? all are phrases that have been used to describe America's most cherished ideals over the centuries. But who first gave voice to those notions, and how did they become part of the nation's culture? Those are the questions that writer Neil Baldwin explores in his book The American Revelation: Ten Ideals That Shaped Our Country from the Puritans to the Cold War (St. Martin's Press).

Neil Baldwin began searching for the roots of American idealism after learning more about the origins of the phrase, "city on a hill." The phrase has been a popular way of referring to the United States ever since President Ronald Reagan's 1989 farewell address to the nation, in which he noted that throughout his political career, he had used it as a way of describing the country:

"In my mind, it was a tall proud city," President Reagan recalled, "built on rocks, stronger than oceans, windswept, God blessed and teeming with people of all kinds, living in harmony and peace."

While Ronald Reagan's "city on a hill" captured the imagination of the 20th century public, it was one of the first English colonists in America who turned that image into a metaphor for the future nation. Neil Baldwin says the phrase dates back to the New Testament. "It's actually from the Sermon on the Mount, and then it was picked up by John Winthrop, who was the leader of the Puritan Great Migration in 1630, and gave a sermon in which he says 'we shall be as a city on the hill, and the eyes of all nations will be upon us.' And it inspired me to look back at people who have been relegated to the second rank of historical players, but who I felt were important in terms of the ideals they introduced to our culture."

In The American Revelation, Neil Baldwin profiles idealists as diverse as John Winthrop; Jane Addams, whose 1889 Chicago community center launched a new era of women's activism; and historian Carter Woodson, who created Negro History Week, now Black History Month.

If any of the ideals in the book stands at the core of the American character, Neil Baldwin believes it is the notion of self-reliance, first put forth in a speech and then an essay by the 19th century writer Ralph Waldo Emerson.

"He is responsible for importing essentially the whole core philosophy of Romanticism from Europe to America," Mr. Baldwin explains, "and transforming it into what we now think of as the Transcendentalist movement, which is basically a very spiritual way of looking within yourself and improving your life by first of all tending to your own spiritual well-being. So I think self reliance today, a 150 years later, is still a core principle in the way Americans think of themselves."

Many of these idealists were expanding on ideas that had already been introduced by other people in other parts of the world, which is a very American tradition in itself, says Neil Baldwin. "We like to think of ourselves as a nation that's different. But in fact, we're also a nation that is a synthesizer of many outward influences, and of course people from around the world, which is why The Melting Pot is in there, a play that was written by Israel Zangwill, who was an English Jewish intellectual who was infatuated with America. And I thought it was great that the image that sums us up as a combination of so many different kinds of cultures and peoples and nations was created by someone who wasn't even an American citizen."

Some of the ideals in The American Revelation have inspired controversy and debate over the years. Nineteenth century newspaper editor John O'Sullivan proposed the notion of "manifest destiny," meaning that as America expanded its borders, it would also expand the principles of liberty and democracy. To some, manifest destiny would become synonymous with imperialism. But regardless of what happened to the ideals they espoused, Neil Baldwin believes the idealists themselves all shared at least one common trait. "The one thing all these people had in common was that they had the courage of their convictions at the time they decided they wanted to stand for something, and they found the vehicle in the culture that allowed them to express this conviction."

Neil Baldwin ends his book with a profile of George C. Marshall, the revered World War II general who went on to become U.S. Secretary of State and devise a massive economic plan to rebuild post-war Europe. He made the case for his plan in a 1947 speech at Harvard University, declaring that "with foresight and a willingness on the part of our people to face up to the vast responsibilities which history has clearly placed upon our country, the difficulties I have outlined can, and will be overcome."

Neil Baldwin notes that George Marshall went on to win the 1953 Nobel Peace Prize. "And when he received the Nobel Prize he accepted it on behalf of the American people because he said that he would not accept this prize for himself. He said, the American people are very generous people and I'm taking this back to them as a country."

With profiles that span more than three centuries, The American Revelation suggests that American ideals have taken shape slowly over time, and Neil Baldwin says their role in the nation's history has never been constant. "They can become forgotten. And they can become ennobled. They can become perverted. They can become resuscitated. They can die off and be under the surface. And my hope is that people reading the book and revisiting the ideals will bring life to them."

Neil Baldwin believes it is possible to see a modern day version of American idealism in the recent outpouring of support for victims of the tsunami in Southeast Asia. Those who rushed to help may not have known it, but they were reflecting some of the same principles the author writes about in The American Revelation -- from the New World hopes and dreams of John Winthrop to the global vision of George Marshall.