Ms. Gladstone sells Meier condo.

Veteran gallery owner Barbara Gladstone doesn't only love art and artists, she's also shown a strong commitment to starchitects. After buying a condo at Richard Meier's 165 Charles Street in 2005, she tapped rising star Annabelle Seldorf to design her Chelsea gallery, which opened in 2008.

But now Ms. Gladstone is leaving behind her glass house along the Hudson River. City records show that she sold her condo, which does not appear to have been listed publicly, for $6.5 million. Not bad, considering that she paid $4.86 million for it, according to city records.

Did Ms. Gladstone want a place where she could display more of her art collection without fear of sun damage? Spreads in the Meier building are awfully sunny, after all, with walls of windows. And can any Chelsea gallery owner really ever stare at the waters of the Hudson without a shiver after Hurricane Sandy?

We don't know many of the details of the unit, which appears to be on the 16th floor, although a broker who works in the building warned us that the listings numbers are notoriously deceptive and often combine disparate units so that units 1 and 6 might be listed as unit 16. At least we know who's moving in. The deed lists the buyer as attorney Sanford B. Ehrenkranz and the BLDG Trust.

There was some speculation last year that Ms. Gladstone may have purchased a townhouse at 344 West 22nd Street after the place was bought by an LLC registered to her gallery's address. And her Brussels gallery is in a townhouse.

People care about Mr. Obrist. At 41, the Swiss-born impresario has spent the past three years as co-director of the Serpentine Gallery in London, and has curated some 150 exhibitions internationally since his early 20s. His reputation is that of a fast-talking, tireless obsessive, and his various activities--which include mounting shows around the world, moderating panels, writing catalog essays, hosting early-morning salons and conducting scores of in-depth interviews with artists and other cultural figures--have made him an improbably influential, globally ubiquitous presence in the art world.

After making his first bit of noise as a curator in 1991 with a group show in his kitchen that featured, among others, Christian Boltanski and the duo Fischli/Weiss, Mr. Obrist quickly made a name for himself as a self-consciously innovative exhibition-maker interested in working closely with artists and mounting shows in unconventional spaces.

"There's a certain kind of curator who is really down with the artists, and Hans Ulrich is definitely down with the artists," said the downtown gallerist Jeffrey Deitch. "There are many other curators who keep their distance, simply because it's their personality or their background or because they think that's what one should do. They're not on the scene. You're not going to see them at a party at 1 a.m., deep in discussion."

The interviews Mr. Obrist has conducted over the years currently add up to some 2,000 hours' worth of tape. A fraction of them have been published in books and magazines, but the vast majority remain in Mr. Obrist's personal archive. Through these interviews, Mr. Obrist has established himself as the unofficial secretary of the contemporary art world. "The way we might read Vasari for primary information on the Italian Renaissance," said Mr. Deitch, "people will be looking at the archive of Hans Ulrich's interviews to construct the art history of this era."

For all that, Mr. Obrist remains all but unknown to the general public.

"Sometimes people who are a little bit below the popular radar are actually more powerful than people everyone knows about," said Paula Marincola of the PEW Center's Philadelphia Exhibitions Initiative, who edited a 2006 collection of essays on curatorial practice. "In our field, he's kind of a rock star."

In that capacity, Mr. Obrist has functioned as a "catalyst," according to the artist, critic, and White Columns director Matthew Higgs, but at some point during his career, "this other thing happened, which is that this character emerged, ‘Hans Ulrich Obrist,' who is clearly at the center now of all this activity and is as well known as a lot of the subjects of his interviews, exhibitions, and research."

Earlier this fall, Mr. Obrist was named the most powerful person in the art world by the British magazine ArtReview, bumping the fellow who topped last year's list, Damien Hirst, down to No. 48. The U.K.'s Independent wrote at the time that Mr. Obrist's placement was evidence that "it is curators rather than artists who are now regarded as the real movers and shakers of the art world."

THOUGH HE GRADUATED with a degree in economics and social science, Mr. Obrist was set on being involved with art from the time he was a teenager, and made himself known in the art world at a young age.

"He was this enthusiast, you know? This kind of genius thinker who was very hyperactive," said gallerist Barbara Gladstone of Mr. Obrist's first few years on the scene. "He read voraciously-he'd wake himself up in the middle of the night to read. He had this huge library in Switzerland, which wasn't so much where he slept as where he kept his books."

At this early point in Mr. Obrist's career, no critic or scholar had thought to study the role of curators in art history, and while there was plenty of secondary literature on museums as institutions, there was no book one could read to learn about milestone exhibitions or the history of curatorial practice. Mr. Obrist was surprised to discover this state of affairs when he resolved, in his early 20s, to learn everything he could about his chosen line of work.

"At a certain moment, when I started doing my own shows, I felt it would be really interesting to know what is the history of my profession," Mr. Obrist said in a phone interview last week. "I realized that there was no book, which was kind of a shock."

Mr. Obrist was not the only one who had this experience. In New York City, a young gallery director named Bruce Altshuler found himself in the same position, and in 1989 quit his job to research a book on the history of exhibitions that became 1994's The Avant Garde in Exhibition.

"I was working in a commercial gallery, so I was seeing the role that exhibitions played all over New York in terms of the functioning of this overall system," said Mr. Altshuler, now the director of the museum studies program at N.Y.U. "Art history tended to be written monographically: most of the effort in the discipline had gone into studying individuals and their works, rather than looking at the system of display and distribution of those works."

Mr. Altshuler's book was followed two years later by another milestone text, Thinking About Exhibitions, this one an anthology of essays on exhibition practices edited by the independent curator Bruce Ferguson, the art historian Reesa Greenberg, and British museum professional Sandy Nairne.

This flurry of scholarly interest in the work of curators and the history of exhibitions--now a burgeoning field within art history--came as a result of several factors, starting in the 1980s with the emergence of a class of independent curators who saw the exhibition as a medium unto itself and were driven to experiment with it.

These curators collaborated more with artists than traditional museum curators ever had. They weren't merely taking care of collections, but commissioning original work and organizing group shows around sophisticated themes. As the contemporary art world exploded in size during the 1990s, international biennales proliferated--there are now more than 150--and became platforms for ambitious emerging curators who wanted to showcase their curatorial voice and vision. Curatorial-studies programs, where students learned the trade and thought critically about the practice, popped up all over the country. 

"In many ways, curators took on the role of what we might have once thought of as a role of the critic," said Tom Eccles, the executive director of the Center for Curatorial Studies at Bard College. "Someone like Clement Greenberg was able to codify moments in art and promote individual artists into groups, and say, 'This is what is significant in our time.' I think there's a moment in the '80s when that transfers over to curators."

BY THE TIME Mr. Obrist read Mr. Altshuler's book and the Thinking anthology, he had already begun making his own contribution to the field by interviewing the generation of '60s curators--men his grandfather's age, like Walter Hopps, Pontus Hultén and Harald Szeemann--who had inspired him.

"Exhibitions are kind of ephemeral moments, sometimes magic moments, and when they're gone, they're gone," said Mr. Obrist. "I wanted to find a way of recording this. And since there weren't any books, I thought a good way would be to do an oral history, to start to speak with all these pioneers who had been somehow forgotten. ... It was the last moment when one could get a really firsthand account of the history of curating in the 20th century."

Starting in 1996, some of the interviews started appearing in ArtForum, and this fall, 11 of them were collected in a book called A Brief History of Curating. It is Mr. Obrist's third collection of interviews--the other two are with artists--and an informal survey this week made it seem like basically every curator of contemporary art in New York is either currently reading it or already has. Though it is hardly the first time someone has published a collection of extensive conversations with curators--see Carolee Thea's 2001 book Foci and her recently published follow-up, On Curating--Mr. Obrist's book is nevertheless being called a landmark work, in part because so many of the people in it have passed away in recent years.

Norton Batkin, the founding director of the curatorial-studies program at Bard, called it an "invaluable contribution," and praised Mr. Obrist for getting his subjects on tape while they were still alive. "Other people didn't think of interviewing curators," Mr. Batkin said. "It's a history that in some sense wasn't there before."

And yet, Mr. Obrist is decidedly not a historian. Rather than synthesizing primary-source material and making arguments about what it means, he merely generates that material and moves on, hoping others will pick up the ball. Throughout his career, he has made little of his own views on art, asserting his taste through exhibitions, to be sure, but only occasionally writing argumentative essays of the sort one might expect from a man famous for his rigorous engagement with ideas. In effect, Mr. Obrist functions as something like a neutral mediator--a listener who asks questions of others and provokes them to explain themselves while keeping his own beliefs to himself.

That he has managed to become as famous and influential as he is in spite of that role is what makes him a singular figure in the art world, and a poster boy for how much that world has changed since the days when curating was considered just a job.

"Anybody who pumps a lot of energy into a situation, anybody who expresses interest in other people and brings good things out of them ... is bound to be a player of a special variety," said Robert Storr, the curator, critic and current dean of the Yale School of Art. "The ability to generate excitement, to focus attention and to stir things up in a positive way is a particular skill, you know, and it is not to be taken lightly. We need animators. We have too many of them who have no seriousness and no curiosity, who are just making events and spectacles. He's an animator who actually creates interesting situations."

lneyfakh@observer.com