Go to any great city now and the major shops are fewer than they used to be. In LA, three (Heritage, William Dailey and Michael Thompson) have gone to private addresses in the past couple of years. London has fewer than it used to, although the ever - ambitious Bernard Shapero is attempting to reverse the trend, and Cecil Court - a smaller, more select version of the old Charing Cross Road - remains delightful in its variety. Perhaps only Paris (as ever the exception) retains open shops in quantity - although there too the occasional misanthropic owner makes you wonder why, and how, the tradition keeps going. It seems easier to retreat behind closed doors, where you can choose your friends.

But reality does intrude: booksellers need customers, and customers want to look at the books and meet the person selling them; and the only way to meet new people if you don't have a shop is to exhibit at a book fair. Transporting your best books to the other side of the world, setting them out as seductively as you can, letting the visitors look, touch and admire (or disparage) them, and then shipping almost the whole lot home again - it's the price you have to pay for meeting two or three new collectors who might appreciate and understand what you have to offer.

Incomprehension is, I'm afraid, part of the texture of book fairs. Some years ago I had a copy of Ludolf's Lexicon Æthiopico-Latinum (London, 1661) at the Los Angeles fair. Along came surely the most likely customer in the world - a white Californian Rastafarian with braided hair down to his waist. In response to his request for anything on Ethiopia I showed him the book. What is it? his companion asked. "It's a history of Ethiopia," he said knowledgably, put it back and walked on. I would have thought that the clue was in the title, but there was no point in arguing.

So what of the state of the antiquarian trade, or at least its more expensive end? At the annual London book fair at Olympia, 4-6 June, there will be the usual mix of hopes and fears, magnificence and dross, fascination (to some) and dullness (to others). People have bought old books longer, and more faithfully, than they have traded any other antique object; they will keep on doing so, even-indeed especially - though empires should fade away. The immediate future seems dark, with declining wealth and literacy challenging the dealers to keep their spirits up and make a profit. But the human spirit seems to like collecting, and whoever responds to literature will pick up an early edition of a book they know and feel that it has, somehow, become more alive.