If you should pass through Market Square at one of the more ungodly hours, you might find it hard to believe that, in the morning, those skeletal frames of metal and wood will be brimming with flowers, pottery, bread, gemstones, and books. Go down to Market Square at a time socially acceptable, however, and you will probably find at least one bookstall, maybe two or even three, clustered in the north-west quadrant of the forum, behind Great St. Mary's and Paperchase. Unlike the midnight burger vans, they do not bookend (if you'll forgive the pun) the marketplace, sullenly facing away from each other; in fact, they coexist in apparent harmony, neither one begrudging the other's customers, probably because they are their customers as well.

I bought second-books sporadically in first year, instinctively revolting against the literary graffiti of previous owners. Having learned to love, or at least tolerate the marginalia, I now visit the bookstalls every day, often just to ghost around and browse. The rewards are obvious: for £10, you could buy a book from Heffers, or four or five from one of these wordmerchants. Of course, their range is only a fraction of Heffers', and the turnover of stock can occur at around the rate of glacial drift, but this is part of the fun. Limit of choice is not always a bad thing, especially when it helps you to sniff out those valuables that you might otherwise have overlooked. And there's a real thrill in the unpredictability of it all - when I woke up a couple of Tuesdays ago, for example, I had no idea that I would end the day having procured Roy Foster's W. B. Yeats: The Apprentice Mage - an offer that I'd passed up before, and regretted. Sometimes we do get second chances.

One bookstall is particularly good for surprises. It deals in paperbacks on Tuesdays and hardbacks on Thursdays; not, however, on every Tuesday and Thursday. It is run by a taciturn elder with longish, whitish hair, whose name I have never thought to ask. I don't know where he is or what he does the other five days of the week, but for every appearance in Market Square he somehow magics up a whole new stock. It was at this bookstall that I once encountered Clive James, poet, memoirist, media personality and alumnus of Pembroke. When I dared to approach him for an autograph, he spotted the Collected Poems of Louis MacNeice under my arm: "I see you've got the magic passport," he observed, as I recalled that he was a disciple of MacNeice. "Are you a writer?"

"In a very amateur sort of way, I said."

"Become professional, then," he commanded, and made his purchases.

I have had similarly unexpected meetings at the other bookstalls, which all function as a crossroads for bibliophiles on their travels across Cambridge. And the mysterious allure of the booksellers remains intact, as every day at four or five o'clock they gather up their wares, presumably into a van, and disappear into the evening.