Clifford Ackley keeps his shoulders hunched as he walks. He moves slowly, stiffly, as if he were a school kid headed to the principal’s office. But this isn’t supposed to be punishment. It’s a schmooze, a reception held so the longtime curator can lead a group of Museum of Fine Arts supporters through his massive Rembrandt show.

Ackley nurses a glass of Perrier in the museum restaurant. He wears a brown corduroy jacket, wool trousers the same color, and a dark tie. His lone stylistic flair is the palm-sized Rembrandt button pinned to his lapel. Though he has worked at the MFA for 40 years, Ackley negotiates the room cautiously, generally keeping to himself. Even praise is handled with cool detachment.

Alan J. Dworsky, the fund manager who has established a curatorship at Harvard’s Sackler Museum, reaches out to shake Ackley’s hand. Dworsky tells him he’s heard that the Rembrandt show is doing well attendance-wise. Ackley doesn’t crack a smile.

“I don’t look at those figures,” he shrugs.

Some curators long for the spotlight. Clifford Ackley seeks the shadows. This is, in part, what the job requires. As the curator in charge of the MFA’s prints, drawings, and photographs department, he oversees a collection stretching 500 years, from a 15th century German engraving, “Master of the Stags,” to a Roger Tibbetts etching done this year.

But the work is largely unseen by the public. Unlike the large Impressionist oils that hang in the museum, Ackley’s most coveted work must be kept under wraps. Drawings and prints fade if exposed to too much light. So the print department is a fitting place for a man who admits that back in the 1960s, when he was in graduate school, he considered not taking a museum job because of the social demands.

“Some people like parties and being on stage,” Ackley says one afternoon in his office. “It’s not something I’ve sought.”

Not even Ackley could avoid the attention generated by his latest show, “Rembrandt’s Journey: Painter, Draftsman, Etcher.” Since opening in October, the exhibition, five years in the making, has been praised in the pages of The New Yorker, The New York Times, and the international press.

Ackley gave an on-camera tour to Morley Safer for “CBS Sunday Morning.” The exhibit could be the MFA’s most commercially successful show of 2003, provided it draws 140,000 attendees by its Jan. 19 close. The exhibit is closing in on 100,000, museum officials said last week.

While not a blockbuster by Monet standards, it’s a success for a show with works, in some cases, as small as postage stamps.

Ackley insists he doesn’t care much about ticket sales. What he’s proudest of is the show’s scholastic merit, and the 304-page catalog he helped write. And even though Rembrandt shows have framed his career — the first in 1969, the second in 1981 — Ackley resists the notion that the current exhibition might be some kind of career-capper. Never mind that he’s 66 and the show was an enormous undertaking. Or that last summer Ackley had heart surgery.

Has he considered stepping down?

No, Ackley says. He adds that it’s not a subject he wishes to talk about.

“I don’t think he’s anywhere near done,” says Lois Torf, a museum trustee and longtime fan of Ackley’s work. “But I do think this is a culmination of all of his serious thinking about Rembrandt.”

It should hardly be surprising that Ackley keeps his plans to himself. He lives alone and is proudly private, a virtual mystery man even to those he considers closest. Take Stephanie Stepanek, an assistant curator. She was at the top of a list of 10 people Ackley provided to talk about him.

“I don’t really know him that well,” she says. “I know what his interests are but he’s private. He’s not like a lot of people.”

Ackley doesn’t hide his reclusive nature. He says it’s rooted in his childhood, which is one of the few pieces of personal information he does enjoy sharing. He hopes to one day write a memoir about growing up on a farm in Tillamook County, Ore. His mother, Mildred, was the daughter of the farm boss. His father, Sigfrid, was a farmhand. Mildred died when Clifford was a baby, and he was reared by his grandfather, an ultraconservative, self-made man.

Tillamook was famous for its cheese — the high school football team was called the Cheesemakers — and not particularly welcoming to a kid who loved art.

So Ackley spent a lot of time alone, reading Sherwood Anderson’s “Winesburg, Ohio,” and learning to draw. He traveled with his grandfather to Mexico, and at one point decided he would become an archeologist. He also wanted to be a Hollywood set designer.

At the University of Oregon, Ackley moved away from his plan to be an artist. His adviser pushed Ackley to attend graduate school at Harvard. He applied for a Fulbright grant, got it, and chose to study in the Netherlands, leading to a lifelong relationship with Dutch art. While at Harvard, Ackley began to visit the MFA.

In 1966, he was hired by the MFA to work with old master prints.

“But they got someone who, unbeknownst to them, was also really interested in contemporary art and photography,” says Ackley.

His inspirations At the MFA, Ackley’s domain is the print room, where visitors can view the museum’s approximately 200,000-piece collection of drawings and prints. On a recent afternoon, the curator has Patrick Murphy, who runs the room, assemble a group of works Ackley believes reflect his acquisitions. As he promised, Ackley offers works that show his interests reach far outside his very specific, academically trained specialty. The works also burst the public perception of the MFA as a place that began collecting contemporary art only recently. There’s a Willem De Kooning, which Ackley acquired in 1970, and a Jasper Johns.

“That’s the one thing that’s so phenomenal about him,” says gallery owner Barbara Krakow, who has known Ackley for years. “Clearly, his scholarship is in material like Rembrandt. Yet his knowledge of contemporary art is vast. Of all the curators in the city of Boston, Cliff is the one that is most out looking for work. I see Cliff more than anybody.”

He might do Newbury Street on a Saturday, showing up at Howard Yezerski’s gallery with bags from a day of shopping. They met back in the 1980s, when Yezerski told him he had a show featuring photographer Jim Goldberg. Ackley agreed to a visit.

At the time, Yezerski’s gallery was in Andover, a good 30 minutes from Boston. Ackley has never had a driver’s license. So one afternoon, at the end of the day, Yezerski drove his tan minivan to the MFA and picked up the curator.

“People can be intimidated by him, by his guardedness,” says Yezerski. “They would say, `My God, what do you talk about in a car going both ways?’ “

Ackley knows that he’s sometimes considered distant. That doesn’t mean he accepts it.

“Once, an acquaintance said to me, `You’re like a Buddha,’ ” he says. “I said that inside, I feel more like Egon Schiele,” referring to the German Expressionist whose sexually charged work once got him jailed.

Ackley’s admirers — and there are many, both in and outside the museum — point out that the curator is not at a loss for words with people he knows. They also talk about Ackley’s love of everything visual, whether an 18th-century print or “Toy Story 2.”

“It’s no mistake that he starts out the Rembrandt catalog with a film analogy, which might make an art historian cringe,” says William W. Robinson, curator of prints at the Harvard University Art Museums, who worked with Ackley on “Rembrandt’s Journey.”

Ackley’s enthusiasm for film, his admirers say, is very much rooted in his emphasis on the visual. They say that his desire to understand a work on his own terms — without words but by staring it down — leaves him receptive to a range of work a traditional art scholar trained in 17th-century work might ignore.

Not about to be boxed in, Ackley managed to recently curate a show of contemporary art, called “Visions and Revisions: Art on Paper Since 1960,” largely made up of works he acquired for the museum.

Saundra Lane, a photography collector, says that the exhibition was one of the best she has seen in a long time. “You can’t question his judgment,” she says. “He has an eye, you’ve heard that term 3,000 times, but he’s got it.”

Ackley’s approach There is no back-slapping in Ackley’s world. Instead, he’s nurtured a group of patrons through his more personal, small-room approach. He makes house visits, and, like many curators, accompanies collectors to the art markets. Whether talking one-on-one or giving a lecture, Ackley speaks in a low voice sometimes delivered painfully slowly. He’s not a smooth talker, but his friends point out that he can be funny in a bookishly witty way.

Ackley’s approach has helped him recruit supporters not only to help build one of the museum’s most varied collections but to develop the room in which it’s available for viewing.

A donation from Richard and Claire Morse led to the creation of the print study room built in 1997. There, four days a week, works can be viewed by appointment. About 2,000 people use the print room each year, according to the MFA.

Ackley’s supporters have also made sure he remained in charge of the prints, drawings, and photographs department, even during the MFA’s famous 1999 reorganization. Director Malcolm Rogers, in an interview, praises Ackley without outlining why he remained at the museum while other veteran staffers were let go. It helped that when Lane endowed a photography curator’s post in 2001, she says she reminded the MFA that she wanted Ackley to stay as head of the department in which the new curator would work.

Of course, other supporters think Ackley’s style — not flashy, content to remain in the background — helped him survive the changes under Rogers. He knows that to be favored at the MFA, he can’t be stubborn even when it comes to developing exhibitions. Rembrandt, for example, started as a show of prints only.

Then Rogers told Ackley to include paintings and drawings. The curator wasn’t pleased, though in the end, he believes including a range of work made the show better. It also helped reveal the Rembrandt that he knows, the artist whose range and skill were limitless.

“I don’t think of Rembrandt as a dead artist,” says Ackley. “I think of him as very much alive.”

It is in the galleries that Ackley comes alive. Standing in front of a crowd of about 50 museum supporters, Ackley talks nonstop for the better part of an hour. Some of the anecdotes are familiar, but he is not working off a script. He keeps the crowd on its toes with the sort of colorful language one might not find in an art history book. About a drawing of Adam and Eve, he smiles and offers his own critique.

“Eve presents the apple and she’s a good salesperson. She has the apple held above her breast like a third breast. Adam, amazingly and amusingly, is a terrible wimp.”

There are chuckles through the group, which includes such heavy-hitters as MFA Board Director John Cogan Jr. and Richard Morse, the print room donor.

As he stands with his Rembrandts, Ackley’s words flow, his smile emerges, he laughs freely. He mimics the moves of an ice skater in front of a painting of a wintry pond. It is as if his joints have been oiled.

He is no longer thinking about the dread he felt earlier at the prospect of yet another tour. He could talk about Rembrandt all night.