But Mr. Pollan winds up broadly playing celebrity chef in “Cooked,” his four-quadrant book about fire (barbecue), water (stewing and braising), air (baking bread) and earth (fermentation). He was prompted to do this, he says, partly by what he calls the Cooking Paradox. There we sit on our sofas, watching cooking shows on television rather than preparing meals of our own. “I don’t need to point out that the food you watch being cooked on television is not food you get to eat,” Mr. Pollan says.

“Cooked” underscores that it has become too easy to unwrap, microwave, order in or otherwise dodge cooking chores — to the point where at-home food preparation skills are simply being lost. It is not encouraging to hear Harry Balzer, a food industry market researcher, tell Mr. Pollan that much of what people now call “cooking” would have grandmothers spinning in their graves.

Mr. Balzer has a cynical suggestion for losing weight, based on his perception of consumer laziness: eat whatever you want, as long as you’ve cooked it yourself. In that spirit, Mr. Pollan goes into cook-it-yourself mode. But he has chosen modes of cooking so demanding that he needs help. So each section has Mr. Pollan learning at the feet (or dough-kneading hands) of a famous practitioner. Then again, no matter how renowned the teachers he chooses, Mr. Pollan is the star of this four-stage cooking show.

It’s unfortunate to begin “Cooked” with a section about fire, since the world of barbecue is such a world of showboating. In this realm, “O.K., but that’s not barbecue,” is a serious insult, and Ed Mitchell, who “just might be the first pit master to have handlers,” refers to his own biography as “the Ed Mitchell story.” Mr. Mitchell drops the word “authentic” so often that Mr. Pollan begins to fear “that I’d opened the spigot on a hydrant of barbecue blarney.” Nevertheless, he ventures to Wilson, N.C., to learn how to cook a whole hog over a fire.

Not all the blarney is Mr. Mitchell’s. The normally common-sensical Mr. Pollan has too much to say about the priestly overtones of this cooking ritual; about the role of meat in mythology and ancient literature (“Achilles served the meat,” Homer apparently wrote); about “the whole vexed issue of sauce”; and the apparently indescribable wonders of the end result. “So this was barbecue” and “there was so much going on in this sandwich” are among his weaker comments.

“Cooked” moves on to a seemingly more commonplace subject: cooking in pots. It’s a nuanced topic, and it’s also the part of the book most apt to teach the reader anything useful. Though Mr. Pollan does not intend “Cooked” as a how-to, he parses the ways diced onions can become a French mirepoix (in butter, with carrots and celery); an Italian sofrito (in olive oil, perhaps with garlic or parsley); or a Spanish sofrito (with tomatoes instead of celery).

Mr. Pollan also addresses larger topics, like the essence of the specific savory taste known as “umami,” the chemistry of why salt makes food absorb other flavors, and the joy of uni-tasking. (“When stirring the pot, just stir the pot.”) But whenever food starts making Mr. Pollan feel “deep Proustian echoes” coming on, it’s time to turn the page.

The book’s baking chapter is its most abstruse, because the endless variables in bread making have such nerd appeal. (Mr. Pollan quotes blog posts that he contends sound less like cooking than like “trying to master a new software platform.”) He spends time with Chad Robertson, a coolly charismatic surfer-baker. Mr. Robertson has written in his own book about why his signature bread is a loaf with an old soul.

There is discussion here of gluten, retronasal olfaction (the reason bread smells good even after it is ingested) and the flour wars between brown and white. And then, finally, it’s time for natto, kvass, smreka, ogi and a lot of other words that belong in crossword puzzles, as Mr. Pollan explores the varieties of fermentation.

It’s a topic explored in “The Art of Fermentation” by Sandor Ellix Katz, who appears prominently here as well (Mr. Pollan wrote the foreword for that book). Mr. Pollan mentions “the erotics of disgust” to the nun who is teaching him cheese making; discusses the health benefits of gut-dwelling microbes that may prevent inflammation; and manages to home-brew a beer that smells like a Band-Aid.

For all the exoticism of this book’s adventures, Mr. Pollan does not stray far from familiar ground. Simple but true: food becomes “literally more wonderful (and wonderfully more literal)” when we remember that who we are and what we eat are parts of the same world.