About a week before the London Book Fair, I had dinner with a prominent editor here in New York. "Are you going to London?" I asked.

"No," she said. "I never go to those things."

She didn't elaborate, so I'm not completely sure what she meant. Was it that she was too powerful to bother going to a convention? Or that she's too shy, by nature? (That's my guess.) In any event, what exactly did she mean by "those things?" Does she avoid all meet-and-greets, or just the ones that involve traveling far and talking to people she ordinarily doesn't see?

Whichever—by the look and feel of the London Book Fair last week, this particular publisher was in the minority. According to reports, overall attendance at the three-day fair was up 4.1%, and international visitors were up 16.8%. Honchos from Jane Friedman to Dan Menaker to Morgan Entrekin were very much in evidence; every major house, many smaller ones, and dozens and dozens of agents were there, too. The London Book Fair has become so popular, in fact, that some wags predict it will soon surpass the Oktoberbookfest in Frankfurt as the international rights convention; next year, LBF moves to new facilities, which should increase exhibitor and office space by about 30%.

All this at a time when book sales are flat, or at least flat-ish, a time of significant anxiety about international travel, a time of such dollar weakness that a Diet Coke in a café abroad can run you $10. Never mind that the book business is supposedly going to hell in the proverbial handbasket—and that everyone has e-mail anyway, all the better to save a few thousand bucks on international travel, hotels, etc: still, the book fair is alive and well.

Why's that? Your numbers guy can make a good case why you shouldn't go, just as he has argued against sending that midlist author on tour. Fairs overseas can cost American companies upward of $3,000 a head, and that doesn't begin to include the cost of building a booth or throwing a party. In these lean times, we should be more practical, more levelheaded, more imaginative than spending money to be an exhausted conventioneer. But to all those who press the bottom-line argument against fair-going, I say: you missed the memo. To wit: this is the book business, not a business business. It's an enterprise run at least as much by gut and heart and luck as by brains and calculation. Sure, it would make more sense to do all your international business on the phone and in e-mail, to limit your printing and mailing expenses to correspondence with editors and agents and subagents whose taste you already know and love. But what fun would that be? Surely not as much fun as that had by the American editor who just so happened to be seated at a European dinner next to a Norwegian agent only to discover that they shared a passion for, of all people, Philip Roth. Much drinking, card exchanging and promise of manuscript-sharing—which might, after all, turn into business—ensued.

The fairs themselves are big business for their promoters—LBF, for example, is a for-profit venture owned by Reed Elsevier, the parent company of PW—but they're also good for the business of attendees in more ways than you might think. While nearly everybody complains about how hard they have to work in the weeks leading up to the fairs and at the events themselves, not to mention how they always come home sick with one or another strain of the Frankfurt flu or a touch of London's chill, the truth is they'd be lost without these thrice-yearly organizing principles (New York! In June!). How many perennially late and overworked editors and agents and scouts use London or Frankfurt or BEA as a way to force themselves to get their lists and their pitches into shape in time to sell? "If it weren't for the international fairs," says one agent, "I'd never put together a clear list of what I had."

But of course, the real value of the book fair—like so many aspects of this business—is far more ephemeral than all that, and far less quantifiable. It's about what you gain in connections—with people, networks and ideas; it's about bonding with other crazy, nonscientific, emotional and capricious book lovers in the pursuit of the business's holy grail: the book everybody loves, the book everybody will someday read, the perennially elusive Big Book. Or a book, simply, that you love.

Like the grail, such prizes are hard to find, but like the zealots we are, we can't help but to keep on looking, booth to booth, party to party, fair to fair.