Surplus Value : GLASS, PAPER, BEANS: Revelations on the Nature and Value of Ordinary Things.<i> By Leah Hager Cohen</i> .<i> Doubleday: 320 pp., $22.95</i>

The poet Keats once described how he felt while reading a new and wonderful author. It was like being an astronomer, he said, and suddenly a new planet swims into view. It was like being an explorer and discovering the Pacific Ocean.

I would use a somewhat different metaphor to describe what it feels like to read Leah Hager Cohen. It’s like watching someone take off in a Porsche or maybe a Jaguar, doing the car equivalent of a treasure hunt. She can go 110 mph through traffic, and all lesser cars fall back on all sides. But the turns! Left here, right there. Left, left, hard right, now at the fork take both roads. Where’s she going, anyway? But, oh, what a beautiful car!

Cohen’s new book, “Glass, Paper, Beans,” opens in a small coffee bar called the Someday Cafe. It is Sunday morning. Every seat is taken and there are people standing waiting for someone to leave. One of the seated people is Cohen. She has a large coffee, for which she paid $1.25; she has the use of a glass tumbler to drink it out of, for which she paid nothing; she has a Sunday paper to read, for which she paid $1.50.

This scene, which takes only six pages, instantly pulls the reader in. Cohen is a superb observer. And she is an equally good describer. The look, sound, feel, smell of the Someday Cafe are all vividly evoked. Even more, so is her state of mind. She’s got good hot creamy coffee, a good seat (“the one facing out”), a good Sunday paper (the Boston Globe). Everything she needs for a pleasant morning.

“But I am not content. I feel obscurely put-upon. It’s this dearth of chairs and this constant minute shifting of the people standing around waiting. I feel the pressure of an unspoken entreaty--to finish my drink and relinquish my seat--and I am uneasy. I do not want to give up my seat, and neither do I want to feel like a hog. I’m conscious of feeling annoyance toward the people waiting for tables. I seem to be annoyed with them for being there, and for not having seats.”

If you can resist the keen insight and the perfect writing of that paragraph, well, I have to suspect you don’t like insight and good writing.

But the Someday Cafe is a mere garage from which Cohen’s Porsche speeds off. She is headed for Canada, Ohio and Mexico. She is going to write a book about glass, like the tumbler she is drinking that good coffee from, and about paper, such as the newsprint the Globe is printed on, and about beans, such as those the Someday’s coffee is brewed from. She is going to make connections to sources.

In general, we Americans have no idea--beyond an occasional Made in China or Made in USA--where the stuff we consume comes from. Let’s get personal. Do you know where the Los Angeles Times gets its paper? Or who made your nice wineglasses, your not-so-nice beer bottles? (What’s wrong with them? They ought to be, and aren’t, made strong enough to survive return trips to the brewery.) If you do, you are highly untypical.

But Cohen is going to learn all that. She winds up in New Brunswick, Canada, getting to know a logger named Brent Boyd, some of whose black spruces wind up as Boston newsprint. And in Lancaster, Ohio, where Ruth Lamp works in the glass factory that makes the tumblers the Someday buys. And in Pluma Hidalgo, Mexico, where Basilio Salinas, a Zapotec Indian, organically grows some of the coffee beans the Someday uses.

All three are simultaneously ordinary and remarkable. Their interwoven stories are what make this book so good, what make people compare Cohen to John McPhee. Almost as good, and certainly worthy of their places in the book, are the three histories she gives: of the discovery and development of paper, of glass, of coffee beans.

But Cohen has a lot more detours she intends to make, and some of them I wish she had cut short or even eliminated. She has a great deal to say about fetishes, for example, and I’d have been glad to skip nearly all of it. I already agreed, before she hammered at it for 20 or so pages, that money is a fetish in our culture and that this has caused us to commodify almost everything, including ourselves.

Again, there are four short interludes, one between each of the sections where the braided stories of Brent, Ruth and Basilio are told. Two of them are pretty interesting--but they still feel like interruptions.

I even have one small complaint about the writing: Every now and then Cohen drops in what is sometimes called a Dillardism. That is, a verb in the fortissimo style that Annie Dillard made famous in “Pilgrim at Tinker Creek.” A Ford truck, Cohen writes, “heaves plumy exhaust into the air.” Excuse me, it doesn’t. Heaving is an on again-off again process, but so long as the engine is running, car exhaust is continuous. Rivers “lick rocks into eggs,” she says. Most geologists think rivers roll rocks along, jostling as they go, and that is what rounds them.

Dillardisms work well in Dillard’s dramatic style but, dropped now and then into “Glass, Paper, Beans,” they’re a distraction, like a handful of Mexican jumping beans tossed in the dinner pot. The recipe was better without them.