THE admiring amateur peering at an ancient volume on display under glass at a library or research center may be impressed, but curious, and ask a somewhat heretical-sounding question:What does it really mean to scholars to use original old and rare books? Are they usable as books and not just display relics? How widely available can they be made, and to what kind of public? With the advent of various forms of electronic communications, we are getting used to separating form from content, the medium from the message. When we say "file" do we mean an electronic file, or the manila pasteboard kind that sits in a drawer? Or do we mean a cute little picture of the manila-pasteboard kind of file, as represented on a computer screen? But a book, especially an old book, is both medium and message. "Text is only part of the book," says Peter VanWingen, specialist for the book arts at the Library of Congress in Washington. An old book is of interest for its paper, its typography, its binding, its provenance - where it has been, in simple terms. "It's fascinating to know where a book has been. When you see a German Bible with an Italian signature in it, for instance, you get an idea of the movement of books across the Continent," Mr. VanWingen explains. Hands-on access to the old books themselves, and not some kind of copy, is of course essential for "the forensics of documentation." For someone studying, say, a Gutenberg Bible, "It's detective work," says William Moffett, director of the Huntington Library in San Marino, Calif. "You put things under a microscope." Each Gutenberg is unique, and a smudge, a fingerprint, a pencil mark can all be valuable clues to a book's history. "If it's a 16th- or 18th-century book, if you hold a page up to the light, you may be able to see a watermark, and that may tell you something important." Sometimes scholars work with old books to compare editions of a given literary text to see how they differ. It's a question of "What did the author intend, and what did the printer do?" says Miriam Mandelbaum, a librarian in the rare-book division of the New York Public Library (NYPL). Ms. Mandelbaum worries, though, that American humanities scholars seem to be getting away from actual work with the ancient volumes. "Scholars are less wiling to deal with things they can't take home with them," and by shunning the original editions in favor of paperbacks with lots of footnotes, they are "losing contact with these intellectual and physical artifacts," she says. What about the sheer fact of holding a piece of history in your hands? "It's hard to say it enhances the scholarly understanding of the book, but everyone feels it," Mr. Moffett says. "I can attest to a sense of awe that comes from leafing through the Ellesmere Chaucer, for example," the sense of readers from earlier centuries that read the book - and maybe left a marginal notation, or a ring from a sweating glass. "People like to handle old books because they feel more in touch" than they would with copies or modern editions, says VanWingen. "Libraries provide the kind of access to the 17th century that a museum doesn't." BUT how accessible can works be made? Libraries and research centers have to be concerned about theft, of course, and the frailty of the volumes in their collections - damage from light, moisture, abrasion. Ironically, though, older books - printed on linen rag or vellum, and bound in leather and wood - are often in better shape than books of the 19th or 20th centuries, with their cloth bindings and alum-sized wood-pulp paper. And at the NYPL, Mandelbaum says, "We may be freer with our medieval books than with 'Alice in Wonderland or another later work, because its text may be available in so many other places than the library's first edition. Stanley Cushing, head of conservation at the Boston Athenaeum, a private research library, puts the question facing the keepers of a rare-book collection like this: "Do you hide it from the public to save it for the scholars of 200 years from now, or display it now and not have anything left? You have to come to a certain balance so that the people who need to see it can see it but so that those who are merely intrigued by it may have to be satisfied with seeing it through Plexiglas." He adds, speaking of his own institution's collection, but probably for old books in general, "They're not really ours. They're here in our care, but they'll be here after we're gone."