It seems hard to believe that, just 10 years ago, when you said “Amazon,” you were talking about a river. Since Amazon.com opened for business, on July 16, 1995, it has not only made its name synonymous with online bookselling; it has transformed the way we talk and think about books.

In fact, while the publishing and literary worlds are still struggling to make sense of what Amazon.com has wrought, the company itself has begun to leave mere bookselling behind. The site now offers 31 product categories, from musical instruments to pet supplies, and it can take some navigating to find the actual books on Amazon.com’s ad-spangled home page. For the first time, last year, consumer electronics accounted for more of Amazon.com’s holiday sales than books. This seems like an inevitable evolution, since books themselves have always been incidental to the company’s real goal: inventing a new model for retailing. The drama of Amazon.com’s stock price, profits, and lay-offs has been an ongoing fixture of the business pages, and what made Jeff Bezos Time Magazine’s Person of the Year in 1999 was not books but money – the illusory billions he made at the height of the dot-com bubble.

But as Amazon.com marks its 10th anniversary with press releases and promotions – a sweepstakes, an online concert with Bob Dylan, celebrity deliveries of customers’ orders – the time is right to ask whether Amazon.com’s greatest legacy will turn out to be the way it changed America’s literary culture. Businesses come and go, and it’s doubtful that Amazon.com will still be a Fortune 500 company a century from now. But some historian of the future will surely ask how Amazon.com changed the way Americans buy, read, and talk about books. Is the rise of Amazon.com, as it often seems, really the beginning of a sea change in literacy and literature – a hinge moment like the invention of lending libraries, or newspapers, or even print itself? Or is it just a new technology of distribution, getting us the same old product in a slightly different way?

The last, modest view is encouraged by Amazon.com’s newly announced “Hall of Fame,” a list of the 25 best-selling authors over the site’s history. The first volume ever purchased onAmazon.com, according to the company, was appropriately tech-savvy: “Fluid Concepts & Creative Analogies: Computer Models of the Fundamental Mechanisms of Thought.” But as a mass audience overtook those early adopters – Amazon.com now has 45 million customers – the site’s best-seller list came to reflect a familiar old blend of self-help (“Who Moved My Cheese?” by Spencer Johnson), genre fiction (Nora Roberts, John Grisham, Stephen King), and children’s books (J.K. Rowling is the top-selling author overall). The “Hall of Fame” suggests that Amazon.com has simply sold people the same books they would have bought in traditional stores: It has taken over mass-market bookselling without changing it.

As so often is the case, however, simple numbers don’t tell the whole story. The real significance of Amazon.com has to do with the ways it has changed the relationship between readers and the traditional holders of literary authority – publishers, critics, and authors themselves. Superficially, this is a story of democratization; as with the Internet as a whole, Amazon.com seems to give individual consumers more information and a wider range of choices. Looked at more closely, however, Amazon.com shows that a greater potential freedom does not always lead to actual consumer independence. In fact, the ultimate effect of Amazon.com may be to increase the power of editors and critics, and to narrow the horizons of the average reader.

This paradox can be seen at work in the most recognizable innovations that Amazon.com has brought to bookselling: sales rankings and users’ comments. Sales information is jealously guarded by publishers – even authors seldom know how many copies their books have sold – and has previously been available to the public only in the form of vague, unscientific best-seller lists. By showing the sales ranking of every title on an hour-by-hour basis, Amazon.com gives a clearer picture than ever before of what people are actually buying. (Though even here ambiguities remain: just how many copies does it take to move a book’s sales ranking by a hundred or a thousand places? Do Amazon.com’s sales mirror book sales as a whole, including stores and book clubs?)

Similarly, by allowing every user to post his or her comments on a book, Amazon.com bypasses the traditional authority of critics. When it comes to a mass-marketed title like Elizabeth Kostova’s “The Historian,” the best-selling new Dracula novel, Amazon.com’s reader reviews probably give the average reader a more reliable sense of whether he will enjoy the book than do the reviews of professional critics. What I.A. Richards called “practical criticism” has never existed in purer form than on Amazon.com, where readers of “The Historian” alternately praise the book (“all the characters in this tale are very believable”) and condemn it (“the story was dry”) in highly pragmatic, consumer-oriented terms.

But in the long term, ironically, these democratizing techniques are not likely to diminish the market-shaping power of publishers, or the taste-shaping power of critics. On the contrary: with more information to process and more choices to navigate, readers will be more in need than ever of ways to narrow the field. The peculiarities of shopping online, where the reader can’t form a rough judgment of a book by flipping through it, only make the need for guidance more urgent. (Even now that Amazon.com makes it possible to read excerpts from many titles, browsing is far more cumbersome online than in person.) Thus the power of traditional authorities, kicked out through the front door, will creep back in through the window. Publishers build “brand awareness” through advertising, publicity tours, and on-site placement; reviewers let readers know what to think about a book they cannot pick up and handle.

This paradoxical democratization may prove to be Amazon.com’s biggest legacy to the literary world, and its most prophetic. After 10 years, Amazon.com is still, to quote Matthew Arnold, “Caught between two worlds, one dead, the other struggling to be born”: it uses digital means to supply an analog product, an old-fashioned paper-and-ink book. But books, unlike pet supplies and Amazon.com’s other wares, are essentially information, which means they can be reduced to virtual form and displayed in any number of forms: on a computer screen, an e-book, a cell phone, or some new, better technology still to come.

Eventually, when Amazon.com’s “search inside this book” feature converges with Google’s plan to digitize the world’s libraries, there will be no more need for a warehouse full of books. Instead, Amazon.com will be able to offer everything ever written, in purely virtual form: a vast Borgesian ocean of text. Whether this will mean the collapse of literacy as we know it, or the beginning of a new and better kind of mastery of texts, we can only know in time – maybe on Amazon.com’s 50th anniversary.