How many books do you have to sell to have a bestseller?

That's probably the question I get asked most often. And while I usually answer with a complicated theorem about relativity and lack of hard numbers and blah, blah, blah, the truly succinct answer—as everybody knows—is "Beats me."

But there's another question I hear on occasion—and it's a far more sophisticated one. "What books will be read in 50 or 100 years?" some people want to know. "What will last?"

Will readers in 2106 look to Tom Wolfe to tell them about life in the 20th century as we look to Jane Austen for the 19th? Will Michael Crichton be the H.G. Wells, Zadie Smith the Virginia Woolf, David Foster Wallace the new Charles Dickens? Will James Frey's A Million Little Pieces float into a new century or into thin air.

Like I said: Beats me.

Obviously, nobody knows exactly what will happen 100+ years from now, book or anything-else wise, but I recently came upon a Web site that lists the top 1,000 titles owned by U.S. libraries that are members of the OCLC, a worldwide library cooperative consisting of more than 50,000 libraries And it's instructive to see just how many of the holdings listed there are old. Pre-20th century old, the majority of them. And some of them—get this!—weren't even originally published in English, and aren't even books (recordings of La Traviata, say, and the works of Wagner).

And while some listings are not at all shocking—the #1 most-owned-by-libraries title is the Bible—there are some that surprised me. Here I was, all set on assuming, knee-jerk—style, that I'd see the names of 1,000 dead white guys, and lo and behold, among the Homers and the Shakespeares are Jane Austen's Pride and Prejudice(32), two Brontës (Wuthering Heights at 28; Jane Eyre at 30), The Autobiography of Malcolm X (351) and Zora Neale Hurston's Their Eyes Were Watching God (473).

It's not just adult authors (and high-end composers) represented here. Harry Potter and the Goblet of Firecame in at an impressive (for a relatively new title) 350, but it's still miles from Mother Goose(the Tomie dePaola version), which is 3. And unless you count the Lord of the Rings as a kids' book (8)—which I don't, really—the next children's biggie is Alice's Adventures in Wonderland at 10.

Then there are some titles that are so surprising, it almost makes me think we're wrong to lament the number of books we publish every year. Who could have known for example, that The Da Vinci Code (469), even the blockbuster that it is, would be more hoarded than, say, the Encyclopaedia Britannica (543)? And I can't help thinking about the longevity of famous rivalries when I notice that F. Scott Fitzgerald and Hemingway are still at it—The Old Man and the Sea, at 160, is within shouting distance of Jay Gatsby's dock (110). Still, I'm trying to stop short of making generalizations and using these numbers to project into the future. It's just too depressing for what we think of as serious literature that Nicholas Evans's The Horse Whisperer is at 700 while Faulkner's As I Lay Dying is 707.

The good news is, I think, that no matter what, people will keep on writing things to be read. To wit: the MLA Handbook for Writers slides onto the list at 186, snug between The Upanishads and Oedipus Rex.