The most agonizing drama in American big business took a bizarre turn last week when Sears, Roebuck & Co. announced it was buying ads in Vogue, Glamour, Cosmopolitan, Mademoiselle and Essence to advertise its new fall fashions.

This picturesque development is among the most recent in Sears's continuing attempts to arrest its painful relative decline. It eclipses by far the year they put model Cheryl Tiegs on the cover of the catalogue, thereby diluting two brand names at once. ''Until they can change their image, telling your wife to shop for fashions at Sears should be grounds for divorce,'' says Kurt Barnard, a retail consultant and veteran Sears watcher.

In the last 10 years, Sears has attempted nearly every kind of corporate refurbishing imaginable. First it set out to become a financial supermarket (''stocks and socks''), then to create the ''store of the future,'' including an improved appliance department featuring other merchandisers' white goods called ''Brand Central.'' Then there was the much-ballyhooed ''everyday low prices'' campaign for the general merchandise stores themselves -- followed by the widespread discovery that Sears prices weren't as low as their competitors' prices, followed by more of the usual sales.

The company wanted to sell the Sears Tower in Chicago and changed its mind, started a big global trading company just like the Japanese, and then folded it. If there was a me-too ploy possible, Sears went for it; executives even talked a Rolling Stone writer into writing an embarrassing puff of a book about how they'd turned ''the store'' around. (That's the kind of mind-bending a $54 billion corporation can do.) Now Sears is understood to have hired Mike Porter, the Harvard Business School faculty whiz kid, who is the latest fad in corporate restructuring, to help design their next move.

About the only foolishness they avoided: They didn't buy American Motors Corp. in 1979, and they didn't get taken over by Robert Campeau.

Can Sears, which once enjoyed a kind of effortless dominion, ever again regain its lofty position as America's flagship retailer?

Despite the spinning, Sears remains a likable company. Its general merchandise stores may not be able to compete on price, thanks to a corporate structure that is simply too heavy, but there is a solid, Midwestern predictability to what you are likely to find in its 403 full-line, 388 medium-size and 779 specialty stores. Its Allstate Insurance subsidiary earned a mere $183 million last year, thanks to an unusually heavy load of earthquakes and bad weather during the year. The DiscoverCard, Sears's entry into the lucrative credit-card business, is performing well, earning $35 million last year, up from $20 million the year before.

All this is the outgrowth of one of the most distinguished corporate histories in mass-marketing. Along with arch-competitor Montgomery Ward & Co., Sears virtually invented the mail-order catalogue business, starting in the 1890s, selling goods to rural America on the basis of its willingness to stand by what it sold. It opened its first retail stores in the 1920s and quickly became the dominant force for putting refrigerators in American homes -- followed by an avalanche of other machines, all brought into being through a remarkable web of relationships with manufacturers and suppliers.

One of the classic sagas of comparative strategy is the story of how Sears correctly diagnosed the explosive nature of the post-World War II world, then built for it aggressively, especially in the South and California, while Sewell Avery at Montgomery Ward sat tight on his cash year after year, expecting a depression. And in the 1960s, Sears all but invented modern consumer credit. Of the $870 million earned last year by the Sears Marketing Group, nearly half of it came from the interest on Sears charge accounts.

But in the 1970s, Sears was outflanked and undercut from nearly every direction. In its trademark hard goods business, heavy discounters like K mart and Wal-Mart moved in, offering a broader array of nationally advertised brand names than Sears's famous private label goods (Craftsman tools, Die-Hard batteries, Kenmore appliances). Soon even more specialized ''category killer'' stores moved in, offering the lowest prices and widest selection in sporting goods, electronics, automotive parts and the like. In the lucrative apparel business, savvy marketers such as the Limited and the Gap took away excitement at the malls, rendering Sears's look hopelessly dowdy. Even catalogue stores reemerged as a force in the apparel market, often beating Sears at its own game. After all, what are Land's End or L.L. Bean except glorified versions of Sears-by-mail?

In the most recent set of moves, Sears Chairman Edward Brennan has personally reassumed control of the merchandising group, from which he ascended to the top job five years ago. A third-generation Sears man at the head of a $54 billion behemoth, Brennan sometimes shocks high-finance colleagues by insisting on walking through Sears stores after lunch, the better to study the fine points. This spring, he declined to turn over the reins of Sears to his older brother, Bernie, who runs Montgomery Ward. (Bernie had proposed a merger.)

Now Ed Brennan must follow in Bernie's footsteps, lopping off thousands of Sears's 337,000 merchandising employees, to get his selling costs in line. He may not have much time. Sears stock last week has dipped below $30 a share; book value is over $40 a share, and breakup value, if its parts were spun out or sold off, could be twice as much again.

According to Richard Tedlow, a Harvard Business School professor who has written a fascinating history of American mass marketing called ''New and Improved'' (Basic Books, $24.95), Sears simply missed the crucial wave. ''The transition from a ... world of big stores selling private label goods to a mass market to a ... world of smaller stores, many featuring nationally advertised brands and moving quickly with the changes in fashion characteristic of the age of television was tougher for Sears because it struck directly at its greatest strengths.'' Sears's physical assets -- its enormous stores and monolithic marketing apparatus -- are anachronisms from an earlier age.

Tedlow's probably right. Still, the game is not over. Putting Sears ads in Vogue is only a few steps removed from putting, say, trendy Benetton fashions in Sears -- it's a change that might take a generation, but it could happen. And there's at least one more big wave to catch.

As Tedlow perceptively writes, much of Sears's success in the years after World War II is owed to its adjusting to a single enormous earthquake in American retailing -- the automobile. Its move into tires and insurance, to the suburbs, to the South and California, were all predicated on a single brilliant intuition.

A retailing earthquake of similar dimensions is in the very early stages unfolding now. It is, of course, the diffusion of the computer -- and among the leading experimenters in videotext services (meaning home sales by personal computer) is an ambitious joint venture by IBM and Sears. Washington-area grocery stores are already marketing this way, through Apple computers with their little icons that permit shoppers to cruise up and down the supermarket aisles at home. Home delivery takes place at a specified hour the next day. Whoever figures out how to conduct home sales in the general merchandise market truly will be operating the store of the future. It may be a little bit early to count Sears out.

David Warsh is a columnist for the Boston Globe.