Editor's note: Nicolaus Mills is a professor of American studies at Sarah Lawrence College. He is at work on a new book, "Season of Fear: 9/11 and the Road to Iraq."

(CNN) -- The battle between President Barack Obama and congressional Republicans over raising the debt ceiling has escalated into more than a fight over the budget and taxes. It has become a battle over who speaks for the American dream -- those who want the wealthy to pay a greater share of the nation's taxes or those who want to cut entitlements such as Social Security and Medicare.

A look back in time provides a view of the American dream that ought to encourage liberals.

The famed historian James Truslow Adams, in his 1931 study "The Epic of America," is credited with popularizing the term "American dream." But Adams' dream had little to do with the now-popular idea of "striking it rich" and achieving fabulous wealth. Adams' version of the American dream was a modest one. It was a shared dream in which men and women attain "the fullest stature of which they are capable" without trampling one another.

Adams was opposed to a system that, as he put it, "steadily increases the gulf between the ordinary man and the super-rich," and in this view Adams was not just speaking for himself. He was describing the egalitarian core at the center of the historic American dream.

In the 17th century, we see this modest version of the American dream most clearly in the "city upon a hill" sermon (a favorite of Ronald Reagan) that John Winthrop, one of the Massachusetts Bay Colony's early governors, gave as the Puritans were on the way to the New World. For Winthrop, it was crucial for the Puritans to remember that theirs was a collective enterprise in which they would succeed or fail by virtue of being "knit together" as one people. Sharing and sacrifice were prerequisites, in Winthrop's mind, for becoming a city on a hill that would serve as an example for others.

"We must be willing to abridge ourselves of our superfluities for the supply of others' necessities," Winthrop insisted.

More than a century later Thomas Jefferson found himself reaching a similar conclusion while serving as minister to France. In a 1785 letter to his friend James Madison, Jefferson expressed his horror at the inequality of life in pre-revolutionary France and then went on to discuss how America could avoid Europe's fate.

"The earth is given as a common stock for man to labour and live on," Jefferson wrote Madison, and then with the vastness of America in mind, he observed, "It is too soon yet in our country to say that every man who cannot find employment but who can find uncultivated land shall be at liberty to cultivate it, paying a moderate rent. But it is not too soon to provide by every possible means that as few as possible shall be without a little portion of land."

Almost a century later, with passage of the Homestead Act looming, President-elect Abraham Lincoln expressed similar thoughts. "I have to say that in so far as the government lands can be disposed of, I am in favor of cutting up the wild lands into parcels, so that every poor man may have a home," Lincoln told a cheering Ohio audience.

On July 4, 1861, in a special message to Congress, Lincoln went even further in describing the government's obligation to its most vulnerable citizens. In an address devoted to justifying the Union cause, Lincoln defended the idea of "government whose leading object is, to elevate the conditions of men -- to lift artificial weights from all shoulders -- to clear the paths of laudable pursuit for all -- to afford all, an unfettered start." It was this view of government that in Lincoln's mind made the Civil War a "people's contest."

Nearly 75 years later, with unemployment at 25 percent, President Franklin Roosevelt advanced a similar description of government. In his 1933 inaugural address, Roosevelt spoke of the need for the country to move as an army "willing to sacrifice for the good of a common discipline," and over the next 12 years, Roosevelt never backed away from that idea.

Campaigning for the presidency in 1936, he assured voters, "Your government is still on the same side of the street with the good Samaritan and not with those who pass by on the other side," and in his triumphant second inaugural, Roosevelt made it clear what being a good Samaritan meant in the middle of the Great Depression. "The test of our progress," he proclaimed, "is not whether we add more to the abundance of those who have much; it is whether we provide enough for those who have too little."

World War II only heightened Roosevelt's egalitarian beliefs. In his first fireside chat after Japan's surprise attack on Pearl Harbor, Roosevelt told the nation "ahead there lies sacrifice for all of us," and in his 1942 State of the Union address, he spelled out what sacrifice now meant. "War costs money," Roosevelt reminded Congress and the nation. "That means taxes and bonds and bonds and taxes. It means cutting luxuries and other nonessentials."

For Roosevelt, the notion of carrying on a war while simultaneously cutting taxes was unthinkable and unpatriotic.

Whose vision of the American dream will prevail in the budget battle between Obama and congressional Republicans is far from clear. Both sides, who are still "far apart," as the president put it, may end up compromising their beliefs to get an agreement.

But in the meantime we should have no doubt about the American dream. For four centuries, it has rested on the idea that government should do all it can to narrow the divide between those at the top and those at the bottom of society.

The opinions expressed in this commentary are solely those of Nicolaus Mills.