Merrill Peterson, a historian who enlarged the scope of Jeffersonian scholarship with a pair of books, one tracing the various and often contradictory perceptions of Jefferson during the century and a quarter after his death, and the other a magisterial biography, died Sept. 23 in Charlottesville, Va. He was 88.

His death followed a bout of pneumonia, his son Jeffrey said.

Peterson, a history professor at the University of Virginia, was a prolific writer whose subjects included the abolitionist John Brown, the great 19th-century orator and statesmen Henry Clay, Daniel Webster, John C. Calhoun, Lincoln and, somewhat anomalously, a calamitous episode in Armenian history. His book Starving Armenians: America and the Armenian Genocide, 1915-1930 and After, published in 2004, was written after he joined the Peace Corps at 76 and was sent to that region.

He is best known, however, for the books about Jefferson, which he viewed as complementary. The first, The Jefferson Image in the American Mind (1960), which began as his doctoral dissertation at Harvard, was awarded the Bancroft Prize, generally considered the most prestigious award for American history. An innovative treatment of the biographical form, it analyzed Jeffersons protean character and intellect, and his influence through American history by surveying how he was written about after his death.

The second, which appeared 10 years later, was Jefferson and the New Nation, a more conventional biography that, at more than 1,000 pages, is viewed by many as an exemplary one-volume life, even though Peterson confessed in it that Jefferson remained, for him, finally, an impenetrable man. In any case, Peterson considered it his most important book.

He broke some new ground and laid out new paths in American intellectual history, said Charles McCurdy, a history professor at Virginia who was a colleague of Petersons. At the same time, McCurdy said, he wrote so people who were not necessarily readers of history would be interested. He added, With every subject, he was very good at the compression of events so he could get to the array of ideas that interested him.

Petersons wife of 51 years, the former Jean Humphrey, died in 1995. In addition to his son Jeffrey, who lives in Falls Church, Va., he is survived by a brother, Ralph, of North Carolina; a second son, Kent, of Lenexa, Kan.; and a grandson.