STEUBEN – Although Donelson Hoopes was known for his gentlemanly manners, he was not a man about town in Steuben. He kept to himself, reading and writing about art and taking care of stray cats. He made weekly visits to the Milbridge Public Library to borrow old war movies or John Wayne hits and to read The New York Times, often complaining under his breath about politics and world events. He was cheerful and polite, but reclusive most of the time.

Last month, when neighbors noticed his lights blazing through the night and the mail piling up in his box, they knew something was wrong and called the police. The Maine State Trooper who responded to the call found Hoopes lying in a pool of blood, still alive but suffering from a fall he had taken several days earlier after having a stroke. He was flown by helicopter to Eastern Maine Medical Center on Feb. 9. On Feb. 22, Hoopes died of complications from the stroke. He was 73.

While Hoopes lived a quiet life in Maine, in the national art scene he was widely respected as a pioneering museum director and art curator. His ground-breaking exhibitions of American art, including shows featuring watercolors by Winslow Homer, John Singer Sargent and Thomas Cole, are his legacy at museums throughout the country. Hoopes authored dozens of art books, monographs and exhibition catalogs that synthesized works of art with history and biography. He contributed to books about museums, collections and art history.

A graduate of the Pennsylvania Academy of Fine Arts and the University of Pennsylvania, Hoopes began his professional career in 1960 as director of the Portland Museum of Art, where he curated important retrospectives of works by Homer and Maine native Marsden Hartley, whom Hoopes had met, before moving on in 1962 to the Corcoran Gallery of Art in Washington, D.C. As curator of paintings and sculpture in the late 1960s at the Brooklyn Museum of Art in New York City, Hoopes spearheaded the acquisition of three important paintings: “The Pic Nic” by Cole, “Pennsylvania Station Excavation” by George Bellows, and “Eleanor and Rosalba Peale: The Sisters” by Rembrandt Peale.

“Each is an icon of its moment and each is an extraordinary painting,” said Linda Ferber, who worked at the Brooklyn Museum for 35 years and is now vice president and museum director at the New-York Historical Society. “Don was in many ways a pioneer with his work, but he was also a pioneer in major ways for how museums collect works now. And his books are classics.”

Chris Crosman, former director at the Farnsworth Art Museum in Rockland, credits Hoopes with coming up with an important phrase about watercolorists.

“Don coined the term ‘the American medium’,” said Crosman, who is now chief curator at Crystal Bridges Museum of American Art in Bentonville, Ark. “He was a pretty important figure for much of his career. But he was an older generation of museum director and curator. As time progressed, the model changed to being strictly a fundraiser. I think he didn’t want to be part of that. He liked to research and write.”

As with many associates and even friends, Crosman didn’t know Hoopes well. They met through a mutual interest in the Farnsworth, where Hoopes sometimes lectured, contributed to at least one catalog and donated a Homer print. Crosman was in touch with Hoopes as recently as last month, when the two talked by phone.

But even those who spoke with Hoopes regularly in Maine said they didn’t feel they knew him well. They were in awe of his expertise in art and appreciated his charm and breadth as a conversationalist. Yet he remained a friendly but eccentric loner.

Jeorg-Henner Lotze, a neighbor and colleague in Steuben, was Hoopes’ closest friend in Maine. Lotze is the founder and director of the Humboldt Field Research Institute, a natural history education center, and the Eagle Hill Foundation, an interdisciplinary offshoot of Humboldt. Both are housed in a rustic setting atop a precipice overlooking Dyer Bay in Washington County.

Hoopes, whose house is on the same road as Lotze’s complex, was a board member of Eagle Hill and attended Humboldt’s heady summer seminars on natural history. At the time of his death, Hoopes was working with Lotze to develop an extensive visual arts component to the organization’s programming. Hoopes left his home in Steuben to Lotze’s organizations with the idea that the roadside farmhouse might be converted into a writer’s retreat for art historians, an artist residence or a gallery space.

“As a result of discussions with Don, interest in the arts developed here,” said Lotze, who lives alone with his Samoyed on the 150-acre Humboldt-Eagle Hill campus. “People need inspiration. People know Maine played a part in the art world. Through conversations with Don, it was apparent we needed to go well beyond what we were doing with workshops and employ artists in a commissioned way, develop a gallery and put things into a larger perspective.”

Though the two worked closely together, Lotze did not have much of a sense of Hoopes’ personal life. What little he knows – that Hoopes was from a prominent Philadelphia family, had one sister (who predeceased him), two former wives, no children, a distant familial connection to President Andrew Jackson and to Fort Donelson, a Civil War battleground in Tennessee – was learned in dribs and drabs from Hoopes, who preferred to keep conversations focused not on himself but on politics and most especially art.

“He had a good sense of humor, a very dry wit,” said Morna Bell, a Milbridge librarian who knew Hoopes casually. She had worried when he didn’t show up for his weekly newspaper-and-movie stint last month. “He liked Cuban cigars and enjoyed his cocktails. But he didn’t open himself up unless he felt comfortable. He had a temper, but he also had a soft side. Don’s clothing was often disheveled, but those things weren’t important to him. Some people might have thought he was eccentric, but I don’t think he cared.”

If locals perceived him as eccentric, it was a powerful enough impulse to make them wonder if his death involved foul play. Although rumors were spread, the police quickly ruled out that scenario.

But no one was surprised to hear that Hoopes had had a stroke.

In later years, his appearance and health, which were affected by psoriasis on his hands and feet and a tendency to overindulge in food and drink, were a far cry from his younger years when he was perceived by colleagues as having a 19th century demeanor, something out of a Henry James novel. Even his handwriting had a calligraphic style.

When Hoopes moved to Maine in the 1990s after working for the Thomas Cole Foundation in Catskill, N.Y., he returned to the area where, as a child, he had sailed and fished with his father. Although he kept in distant touch with associates around the country, his life became more reclusive in recent years. He painted, read, gardened and maintained two antique cars in his garage. Much of his professional energy was directed toward Humboldt and the Green Party.

“Donelson sort of dropped out of the mainstream art world,” said Patricia Hills, a professor of art history at Boston University. “In terms of 19th century American art, he had made major contributions. At one point, he was at the forefront of scholarship in American art.”

Virginia Eskin, a former wife of Hoopes, called Hoopes old-fashioned, even in his professional standards, and said he was disillusioned with the way museum directorships were headed. He had been increasingly tempestuous toward museum work through the years, whether early on at Portland or at posts he held in the 1970s at the Los Angeles County Museum of Art and the M.H. de Young Memorial Museum in San Francisco.

“The niche of museum work should have been all right for him,” said Eskin, a Boston-based pianist and expert in feminist composers. “But the politics drove him insane. He understood Homer and Sargent. They were aloof, alone, misanthropic, misunderstood. He related to them.”

The two remained friendly after their divorce in 1962, and Eskin, who described Hoopes as “Valentino handsome,” said he inspired her to reach higher, to understand art and to develop her own career.

For all the mystery surrounding Donelson Hoopes’ personal world, there is no question about his erudite contribution to the American art scene and his innovative vision for developing an art program in his community. Lotze and Hoopes’ attorney, John Jeribeck, are planning a summer memorial service in Steuben.