DAVID H. Donald, the new Warren Professor of American History, once told a student that he would have preferred life in 1820 America to the modern version. Provided, of course, that he could have inhabited one of the mansions in Beacon Hill's stately Louisburg Square.

Making certain compromises between his ideal and the realities of time and place, Donald seems to have found happiness teaching American history at Harvard.

The scope of inquiry into American history at Harvard has expanded this year well beyond its previous limits with the arrival of Donald, a Pulitzer Prize-winning authority on the Civil War and Reconstruction, and social historian Stephan Thernstrom.

Donald brings with him numerous works on the political, social and intellectual history of the 1861-1877 years--including the Pulitzer Prize-winning biography, Charles Sumner and the Coming of the Civil War.

Donald's quip to his student disciple--particularly his idealization of New England--would probably confuse many of the Harvard students who have already begun to seek him out as a "fellow Southerner." Raised in the hill country of Mississippi and graduated from Mississippi's Millsaps College, Donald retains deep affinities with the people and culture of his native South.

Yet, like his fellow Mississippian, William Faulkner, Donald speaks of a personal ambivalence toward many of the region's values. He cites Faulkner's Absalom! Absalom! as one of the most eloquent expressions of "what it means to be a Southerner."

Like Faulkner's Quentin Compson, Donald traces his historical urge (and that of C. Vann Woodward, Francis Simkins and other historians from the South) to a wrestling with the contradiction between ideals and practice in the Southern experience.

The southern historian, Donald says, begins his search with "an emotional resonance," and southern history becomes a peculiar problem of personal identity. Yet emotional commitment is a basic criterion for historians in general: "You have to have something at stake as you wade through raw material on any topic."

Donald's first historical urge was to write a history of Mississippi. But when he arrived for graduate work at the University of Illinois, he teamed up with Civil War historian James G. Randall, studying Lincoln and the northern radicals. In Donald's academic life, as in the war he studied, the North promptly overran Mississippi.

Since that time, Donald has written almost exclusively about what he calls "the other side"--the North and the Radical Republicans during the Civil War and Reconstruction. While not a southern historian per se, he continues examining the southern people: "I want to know why they responded as they did to Lincoln, Sumner and others. This is part of my own coming to terms" with the southern experience, he said.

Donald will lead a seminar in the Spring on the problems of Reconstruction, and plans a course on the Civil War and Reconstruction for 1975-76.

Donald concludes that "the South" is really many Souths--"I certainly never saw any Scarlet O'Haras when I was growing up"--and that sweeping stereotypes of the region too often reflect simplistic or biased reasoning. He even militates quietly against the typing tendencies evident, for example, among Boston realtors: They took him directly to Mount Vernon replicas when he began house-hunting here and happened to mention his background. "Mount Vernon homes are lovely," he conceded, "but not all southerners live in them."

Donald says he has found historical holes in the prevailing "southern sterotype"--the culturally impoverished region characterized by bigotry, provincial thought and social inequality. "After all, aren't these so-called 'southern traits' something that we all have?" he asks.

And so David Donald comes to terms with his South.

But Donald keeps coming back to that 1820 ideal. In his course, History 165a, "The Middle Period of United States History 1819-1861" Donald affectionately introduced 1820 America as a stable, harmonious well-ordered society.