This city is about to lose its only pre-War cubist painting by Georges Braque.

One hates to see it go.

"Music" (1914) has been hanging at the Phillips Collection since 1953. On Wednesday evening in Manhattan, it will be placed on the block.

Sotheby's, the auctioneers, anticipate that it will fetch between $3 million and $4 million -- though there is, one can't help hoping, a chance they might be wrong. The stock market is gyrating, and many rich collectors are beginning to feel poor. (Last Tuesday night, at Christie's, costly modern objects by Jackson Pollock, Morris Louis, Frank Stella and Mark Rothko failed to find buyers.) Perhaps some angel of a patron will buy "Music" for this city. But do not hold your breath.

Pictures by Ce'zanne, Degas and Picasso -- and "Irises" by van Gogh -- will be included in the sale. But it is the Phillips' little Braque that is on the cover of the catalogue. It is easy to see why.

The painting has a provenance that could not be much nobler. It was selected by Marcel Duchamp, perhaps the most farseeing and intelligent French artist of his time. At Duchamp's urging it was purchased, in the early 1920s, by his friend Katherine S. Dreier. At her death in 1952, "Music" was bequeathed -- through Duchamp, her executor -- to their friend and colleague Duncan Phillips, the courtly Washingtonian who made his red-brick home on 21st Street this city's, and this country's, first museum of modern art.

Duncan Phillips loved the Braque. If you care about his gallery, and his reputation, and the way that our museums survey modern art, you have to dread its loss.

The gap the sale opens is anything but small.

There are other Braques, it's true, in Washington collections. There are 13 at the Phillips. There are five more at the National Gallery of Art. The Hirshhorn Museum and Sculpture Garden owns a few of his small sculptures. But all of these are later things. Lovely though they are, they are not pre-War cubist Braques.

Braque was still a young man when for the first time -- and the last -- he significantly deflected the course of modern painting. That's why "Music" is a monument. The cubist style Braque invented -- in collaborative competition with his painting pal Picasso -- changed the history of art.

How can you comprehend the abstract painting of this century unless you understand the splinterings of cubism? How can you study cubism without seeing early Braques? The answer is you can't.

"Music" is a curious work. It suggests Braque's cool inventions of 1909-1912 while simultaneously predicting the warmer works to come. Its colors aren't all grays; they include rich browns and ochers. Its surfaces aren't smooth, some are rough with sand. The picture's planes are chiseled, as is its violin, its wine glass and clay pipe, but the flaccid "oval" outline loosely drawn around them has the shape of an amoeba.

The plaque that bears Braque's signature confounds the painting's daring; with its nail holes and shadows, it's a small, eye-pleasing joke.

There is one reason only why the Braque is being sold. The museum needs the money. It will no doubt spend it wisely, though exactly how it does so -- on painting conservation, on scholarship and catalogues, or on acquisitions -- has been a matter of dispute between the museum's director and his peers on the national Association of Art Museum Directors. But money is but one part of the story of the Braque.

It seems, at least to me, that the Phillips has decided to part with the wrong painting.

Waiting for the auction is like watching in distress while an old, beloved friend -- one that has been doing exceptionally well of late -- does something sad and wrong.

When Duncan Phillips died in 1966, he left his wife and lifetime partner, Marjorie, in charge. For the following nine years their small museum sort of drifted. Its wealth declined, its plant decayed, its exhibitions wobbled. In 1972, the museum, for the first time, brought a professional on board.

He'd been an assistant curator at the Metropolitan Museum of Art. He did not last for long. In 1975, when it was discovered he had taken 21 prints and drawings from the Phillips storerooms, he was -- understandably -- let go.

It was then that Laughlin Phillips, Marjorie and Duncan's son, took over the museum's daily operations. He was 50 at the time.

"Loc," unlike his parents, had not immersed himself in art. He had fought in the Pacific during World War II. He had then spent 15 years with the CIA, serving in Hanoi and later in Tehran. After that he founded Washingtonian magazine. When he took over the museum, he stumbled for a while. But when he found his feet at last, he began to run.

When one thinks about the nagging problems that he's faced, and of what he has accomplished, it is clear that Laughlin Phillips has done a superb job.

That the Phillips has grown healthier is apparent at first glance. You can see it in the painted, spruced-up galleries, and in the improved quality of the museum's publications. Temporary shows there have handsomely reflected the museum's special character. The staff has been enlarged. And now, for the first time, the museum has employed a renowned art historian. He is Sir Lawrence Gowing, chairman of the curatorial department.

"Our problems go way back," says Phillips. "It was not until I began working here full time that I began to realize how much had to be done.

"The staff was far too small, and on the whole untrained, and grossly underpaid. We had no real catalogue. The building was decaying, and our conservation problems were getting worse each day.

"Our storage conditions were really dangerous. You remember, we were storing pictures in bathrooms and in closets and even in the wood shop. For climate control we had steam heat and window air-conditioning units. It was charming in a way. But it was dangerous as well. And on top of everything, we were running an annual deficit of $150,000. Our $3 million endowment, which at my father's death had seemed adequate, was not producing nearly enough to pay our bills.

"I think we've done pretty well. We've restored about 300 paintings. We've raised $10 million. We've completely renovated the old building. We've put in an elevator, new wiring, a modern climate control system and a new office floor. We've greatly expanded the library. We are well along on a scholarly catalogue of the permanent collection. We've put in a cafe'.

"We're also rebuilding the annex next door. When we're finished we will have, for the first time, proper facilities for storage. We're adding a new top floor for temporary exhibitions. When we're finished with the job, we will have more than doubled the annex's exhibition space.

"All of this has cost a great deal of money -- and more than we anticipated. We had hoped to double the endowment -- a great deal of our program is predicated on having that $6 million -- but we haven't done so yet. We originally anticipated spending about $3.5 million on the annex. It now looks as if we'll have to spend more like $7 million. The endowment has not grown. We've spent what we took in.

"We feel we've left no stone unturned in seeking out the money to accomplish our objectives. We've considered every conceivable approach, from exhausting the endowment to borrowing from banks. Eventually we decided that deaccessioning was inevitable.

"Painfully, at that point, we began to think about what we'd have to sell.

"You can imagine the debates. One school of thought was that we should deaccession eight or 10 lesser works from our larger units of Doves or Marins or Bonnards. But our feeling was that those units were so central to the Phillips that that would be a disaster. So we decided to grit our teeth and pick one important painting -- and to do it only once.

"For a variety of reasons, we decided on the Braque."

Phillips says that installation records show that "Music" was shown rarely with the master's other paintings. "It was a sort of odd man out." "We also know," he adds, "that my father had mixed feelings about cubism. He was far more interested in color, in lyricism and in visual pleasure than in the more cerebral aspects of French painting. And when he felt the gallery needed money, he was quite willing to sell."

Duncan Phillips, it is true, was not particularly offended by the thought of deaccessioning. "Whenever funds must be raised at once," he wrote in 1930, "and whenever we are under unusual financial strain, there is only one thing for us to do -- and that is to sell . . . It is not at all a process of weeding out . . . Only good things sell, and good things therefore must be sacrificed."

Marjorie Phillips, too, was willing to raise money by selling works of art. In 1971, to celebrate the 50th anniversary of the Phillips' opening as a public art museum, she mounted a Ce'zanne show -- and paid its heavy bills by auctioning off Mark Rothko's "Mauve Intersection" for $42,000.

It is also true that Duncan Phillips initially regarded pre-War cubist works by Braque as excessively cerebral and a bit too gray and dry. It was not until the painter returned, wounded, from the war that he began to make the sort of "lyrical and decorative . . . rich and sensuous" Braques that Duncan Phillips loved.

The collector Chester Dale, who bought the National Gallery's Braques, held similar opinions. But Katherine Dreier didn't. She admired Braque's early toughness, and abstract art in general, and had no doubts at all about cubism's significance.

By the end of World War II, Phillips had begun to feel that perhaps she was right.

Soon the two collectors were beginning to fill gaps in one another's collections. Dreier got an Arthur Dove from Phillips. Phillips, in return, bought one of her early cubist pictures, a 1916 still life by Juan Gris.

The gratitude that Dreier felt for her fellow pioneer became apparent in her will. Marjorie told the story: "After the death of Miss Katherine Dreier in 1952, Duncan was astonished to receive a letter from Marcel Duchamp saying that Miss Dreier had left part of her private collection to the Phillips Gallery and asking if he wished to accept the bequest. Duncan was thrilled but at the same time torn -- wondering if he should add en bloc so much of another collection since his own was thus far so personal."

Phillips offered a compromise. Some of the bequest, he suggested, should go not to the Phillips, but to American University. But there was a small number of objects he would gratefully accept. "There are a few pictures," he wrote Duchamp, "that I would love to have in our collection as they are exactly what I would have eagerly bought had I seen them first. I need only mention the early Braque . . ."

The reason its departure does him a disservice is that it somehow seems to strip him, long after his death, of his considered second thoughts.

One last important question swirls around the sale. What will happen to the proceeds?

At first Laughlin Phillips thought he'd put the money into the endowment. But according to the rules of the Association of Art Museum Directors, that was the one thing that he could not do.

The AAMD's policies are clear: When contemplating sales, "exigencies of the moment" are not to be considered. Money got from selling pictures must be spent on buying others. "Deaccessioning shall not serve to provide operating funds, and the proceeds from disposal must be treated as acquisition funds."

That policy makes sense for most large art museums. But the Phillips, so it seems to me, is a special case.

Before Duncan Phillips died, he made his wishes clear. The Phillips, he wrote, is "an intimate personal creation . . . It must in the future be maintained and not altered . . . Such a creation can no more be changed than any fine work of art can be transformed into something different."

The Phillips is so small that it can only show perhaps 200 of its 2,000 pictures. One feels its permanent collection ought to stay cocooned in Duncan Phillips' spirit, and reflect his time.

The Phillips ought to be concerned with the conservation of its treasures, it ought to hire scholars, it ought to have a useful catalogue of the objects that it owns. What it does not badly need is additional works of art.

Last week Laughlin Phillips responded to the AAMD by offering a compromise: "This is what I told them we'll do with the money," said Phillips. " 'In consideration of the guidelines of the AAMD, the trustees have decided to designate a Katherine S. Dreier Fund, and restrict its principal to external acquisitions, circumstances permitting. Meanwhile, income will be used for care and maintenance of the permanent collection.' We've taken a concrete step toward their position. I hope they will agree."

Nobody is happy that the Braque is being sold. Least of all Sir Lawrence Gowing. But he nonetheless accepts that it must be done.

"Our first duty," he explained, "is to perpetuate Duncan's doctrine of accessible household art. Duncan gave the world an art free of dogma, free of suppositions, absolutely without party. His whole collection, its safety and use, is more important than any single picture. We are selling the Braque because we could not think of any other picture that would make so large an amount. That we need to sell is perhaps an indictment of Washington as a source of support for the idea of great collections as voluntary things. Perhaps Washington doesn't want them enough.

"Of course I'll miss the Braque. But its sale will ensure the survival of the collection. And it is likely to be appreciated -- in this miserable circumstance -- more than it has ever been."