The Library of Congress, that elegant bastion of the book in an age of electronic images, has been infiltrated -- some say seized -- by computer people and not everyone is happy about it.

While the library's scholars have been preoccupied with weighty philosophical questions of the ages, critics say a subversive army of technicians has been quietly turning its intellectual treasures into so many electronic bytes, accessible only to those fluent in the glossolalia of Radio Shack. Traditionalists in the Thomas Jefferson reading room mutter darkly of civilization in decline.

"Downright insanity!" protests Ferdinand Stibi, a retired Army historian now stalking the fields of genealogy. "A tremendous blunder."

"A great regret," says historian Barbara Tuchman, envisioning the dehumanization of scholarly research.

Immediate focus of their distress is the computerization of the library's card catalogue, a task of dizzying vastness, under way in one form or another since 1968 and scheduled for completion -- except for editing -- before the end of the year.

Library officials say that the operation is long overdue -- that the card catalogue has been obsolete as both a system and a catalogue for nearly two decades.

"But to some people, it's an icon," sighed Bob Zich, the library's director of planning and development. "It's like a religion."

Launched in 1901 when the library moved into its green-domed building across from the Capitol, the card catalogue is the world's largest: a bibliographer's dream of 60 million index cards, each precisely 75 by 125 millimeters in size, listing every book in the library by title, author and subject.

It overflows the halls and alcoves east of the main reading room in the Thomas Jefferson Building, and to generations of college students and professional researchers its massive wooden cabinets, well-thumbed cards and chest-high writing tables have exuded the very essence of scholarship.

Visibly embodied in its staggering bulk and mind-numbing rows of file drawers loom both the enormousness and accessibility of human knowledge: something on virtually every subject in the world, just a request slip away.

So bookishly hospitable has the catalogue proven over the years that romance often has bloomed from chance encounters among the card files, earning the catalogue an enduring reputation as Washington's choicest intellectual singles' bar.

It is not the threatened social loss that dismays traditionalists in the reading room, however, but the possible loss of something more -- a conceptual transformation of the library itself from a center of literature and thought into an immense data bank.

"The problem with that damn computer is that it will only give you exactly what you ask for," said Arnold Compton of Arlington, a graying, retired school teacher reading up on medieval weaponry. "The real joy of scholarly research is serendipity -- discovering something valuable in the process of looking for something else.

"Browsing through a tray of catalogue cards, you often have your mind tickled by a title or author that has nothing at all to do with what you're looking for. That can get you thinking about your subject in a whole new way.

"You can't do that in a computer, or at least I haven't figured out how. Without that quality of thought, book titles are just so much data."

Library of Congress officials, while not exactly dismissing such objections, say they are made by only a recalcitrant minority of library patrons, most of whom are refusing to deal with the library world as it is and necessarily must now be.

The information explosion of the last 25 years, the officials say, has left major libraries no choice but to deal with the storage and "accessing" of information via methods more efficient than books.

For nearly two decades, librarians here and elsewhere have been far less concerned with books per se than with things like electronic cataloguing, data storage and retrieval and optical discs.

Not only has it become physically impossible to contain and house the yearly incoming flood of new books and manuscripts, they say, but the acid content of most paper manufactured in the last century is already crumbling entire libraries to dust.

Science has found a way to stop that deterioration, and the Library of Congress is building a $12.5 million facility at the Army's former biological warfare center at Fort Detrich, Md., to de-acidify books using diethyl zinc gas.

But so immense is the library's collection that at the treatment rate of 500,000 books a year, it will take 20 years just to treat the books it has. And all the while, the library's whirlwind acquisition program is adding books at the rate of two volumes every second.

Thus, the library is racing against time as well as space, to preserve its information in less perishable as well as more compact form.

The computerization of the card catalogue is only the most visible aspect of a multi-million dollar revolution in what the Library of Congress is and will become.

Already humming away in the basement of the library's James Madison Building is a state of the art data retrieval "jukebox" on which the equivalent of 1.5 million pages of print are stored for virtually instant computer retrieval on laser-etched optical discs.

Deputy librarian W.J. Welsh says the jukebox, part of a three-year, $2.1 million pilot program, is the face of the bibliographical future -- one that could shrink the library's entire 80 million item collection into one of the library's three existing building.

The revolution is so far-reaching that Librarian of Congress Daniel J. Boorstin named a special committee of high-tech heavy thinkers to ponder the very "Future of the Book." The committee's report is due out next month.

And there's more.

Bob Zich, the library's bespectacled director of planning and development, speaks fondly of the day near the year 2000 when the library will be a single enormous information center "possibly under a mountain somewhere," to which citizens will dial long distance to read information they want via a video screen the size of a pocket calculator.

Welsh and Zich speak of such changes as "hospitable technology."

"There's prestige to a computer," says library information officer Craig D'Ooge. "People trust it more than a book. . . . People are more comfortable with a video screen nowadays than a book because of television."

The library officials emphasize it won't be knowledge and information that will change in the new electronic order, only its containers. Every letter of "Oliver Twist" will be as Dickens wrote it, whether between the pages of a book or beamed from optical disc storage to to a video display terminal.

"The question is," Zich said, "will the research library become a museum where books themselves are looked on as exceptional objects" -- valued not for the information they contain (more accessible by computer) but as artifacts.

D'Ooge noted that Boorstin, who established a "Center for the Book" at the library, has been outspoken in his belief that technologies don't really replace one another as much as augment one another, even as radio survived to coexist with television.

Stibi, the retired military historian from McLean, says that may be all very well in theory, but technology also can overwhelm and make obsolete those who can't adapt to it.

He worked at the Library of Congress himself more than 30 years ago, he says, and at that time suggested the computerization of some internal library functions, where he says electronic technology is highly appropriate.

"But for the general library user," he says, "it complicates research more than making it simpler. People have to take a course on working the computer just to find out what books the library has.

"I've seen people who can't deal with computers just walk out of the library. That discourages research and anything that discourages research is harmful."

Tuchman, whose erudite lecture on the book five years ago inaugurated the library's "Center for the Book," says the ease of library computers, not their difficulty, is what worries her.

A single request to the library computer will yield in seconds a detailed printout bibliography of hundreds of books on a given subject, "but when you don't write down your own list you lose contact with what you're doing. The act of writing it down enters it into your cerebellum or something. If it's too easy you don't have to think about it."

While the rapid recall of surveys and statistics may be valuable for congressmen framing legislation, she says, down that electronic road lies "an emphasis on knowledge and information" at odds with the traditional and long-valued concept of a library as a keeper of "literature and the printed word".

"I don't want to offend my friends at the library, but there seems to be less and less recognition there and in the world at large that the whole raison d'etre of the assimilation of knowledge is to 'soothe the savage breast.' " The qualitative difference, she says, is absence or presence of values.

"People have a sense of omnipotence about computers," Tuchman says. "They think if you install one in your home, it will educate your children, balance your budget and settle your marital problems. They seem to be losing the precious understanding that any creative work that can be done must be done by the human mind."

Whatever its many legitimate contributions, she says, "a computer can't help one make moral decisions."

Be that as it may, the new environment of scholarship is as unstoppable as tomorrow.

The existing card catalogue, says deputy librarian Welsh, has had no new entries since 1981. At that time, he said, the personnel and economic resources of the library were bleeding away trying to update it with 2 million new cards every year.

Contemporary library science permits every major library in the country to know the collections of every other -- via a Brobdingnagian tome called the National Union Catalog. The largest catalogue ever printed, it at last count had something like 650 volumes.

As the largest and fastest growing library in the world, the Library of Congress was constantly confounding the union catalogue before computerization.

"So many depend on the catalogue, it has an effect on thousands of libraries every time we sneeze," says Welsh.

Computerization of the library catalogue has thus helped other major libraries, most of which have long since turned their catalogue cards to images.

Readers in the main reading room have been the last to convert, but increasingly staffers have steered them to one of the 40 computer terminals in the library buildings, instructed them in computerese and turned them loose to search the stacks with electrons.

Nobody claims there haven't been problems. The biggest, says D'Ooge, is one of specific subject recall. Readers seeking information about blacks in the United States, for example, must look under "Negroes" and "Afro-Americans" as well. Those seeking books on films must know to look under "moving pictures."

To the unsophisticated, he says, the computer can give an illusion of completeness that can prove deceptive -- library staffers try to assist the uncomputed.

"There are some people who just refuse to learn," says Gary Jensen, head of the main reading room staff. "For a few elderly hard core cases we'll do their keyboarding for them. It takes less time."

Others, whose research is primarily into older books anyway, remain loyal to the old card catalogue, outdated as it may be.

After Jan. 1, however, the computer will be all there is, cataloguewise.

Welsh says the old card catalogue will remain in place a couple of years. "Then," he says mischievously, "we'll move it into the alcoves. We're going to cut back your dosage a little each year."

For him and others at the library, any nostalgia for the old ways have vanished amid excitement for the new.

"It's just progress," says Craig D'Ooge. "You don't see people walking around on Pennsylvania Avenue with cuneiform tablets."