This may not be easy, I realize. "Does that mean that the san marzano has a higher acid content?" I hazard.

Another discussion. "No, it has less acid."

Now I'm confused. If a tomato's sugar content is lower, wouldn't the natural acid be more pronounced? And if so, why would more acid make a better sauce? I persist with my questions, trying not to annoy Savino. (I'm not certain I succeed.)

"The fields are near Mount Vesuvius," Nick translates. "The volcanic soil acts as a filter. The water goes down a couple of feet and...." Nick's hands describe the shape of a circular pool. "So the impurities are filtered out?" I venture. "But how does that make the tomato both less sweet and less acidic?" Nick and Savino chew the apparent contradiction over. "It's bittersweet," says Nick at last.

Still wary about this tomato that Nick and Savino are seducing me with, I begin to track down the san marzano in the U.S.—not a simple task. I discover that the San Marzano legend on an imported can of Italian plum tomatoes may refer to San Marzano the town, not to san marzano the tomato variety, and that the can could therefore just as easily contain roma tomatoes, which are also grown and canned in the San Marzano region but are quite different in taste. Subsequently, using a recipe (at first glance, much too simple) provided by Nick's wife, Rose, I make a basic san marzano tomato sauce that turns out to be absolutely delicious. When made with a can of Progresso roma tomatoes, the results are markedly inferior. For further research, I turn to no less an authority than Balducci's, Manhattan's legendary Italian market. Yes, they tell me, only the best of several brands of imported plum tomatoes bears the varietal name san marzano.

Savino Zuottolo insists that even san marzano tomatoes grown outside San Marzano wouldn't have the same great taste. "I think that's a lot of hogwash," says Professor Charley Rick, a tomato geneticist at UC Davis, when I tell him this. "The genetics of the thing is much more important than the environment," declares the man acknowledged to be the reigning American tomato expert. Next, I talk to plantsman Shepherd Ogden, who grows san marzano tomatoes in Vermont and offers the variety's seeds in his mail-order catalogue, The Cook's Garden. He dissents strongly: "Speak to a wine person," he suggests. "Ask what they think about the importance of the soil." Suddenly, the idea of writing a profile of a tomato no longer seems so far-fetched.

I was aware that Lycopersicon esculentum(the designation translates literally as "edible wolf-peach") had once been viewed with alarm. The first Italian reference to the tomato—by Pier Andrea Mattioli in his herbal of 1544—describes it as both toxic and aphrodisiac. Almost two centuries later, a Dutch herbalist asserted that the tomato's seeds "cause faintness and a sort of apoplexy". What I hadn't realized before visiting the Horticultural Society of New York, however, was that until the 1500s, the tomato was a stranger not only to Italy but to most of the world. "The pomo d'oro, commonly named for its intense deep yellow color," wrote naturalist Costanzo Felici in 1572, was a "singular and mysterious berry" brought home aboard their caravels by Pizarro's conquistadores. Clearly, this fruit, which had already been cultivated in southern Mexico, had changed considerably from the tiny, bright red fruit that grew in the northern Andes—the tomato's place of origin. By the next century, the red variety had become preeminent throughout Europe, but only as a decorative vine, used to enhance arbors, for instance—and even to camouflage outhouses.

Despite the bad press the mysterious berry received, the common people of Spain and southern Italy (where the climate proved particularly suitable to its propagation) insisted on eating it. Then, in 1797, the tomato went uptown when Francesco Leonardi, chef to Empress Catherine II of Russia, included a tomato coulis in his gastronomic encyclopedia, Apicio Moderno. Was it this entry, or perhaps the first published recipe for pasta with tomato sauce (which appeared in Naples in 1839 under the name viermicielli co le pomadoro), that finally conferred respectability upon the fruit that everyone loved to hate? We will never know. But in the country whose cuisine is now unimaginable without them, tomatoes didn't become truly popular until they began appearing as conservati, or conserves—processed and canned (in glass)—in the late 1800s.

From Rome's Fiumicino Airport, I aim my rental car towards Naples. Two hours later, the sign for Salerno and Reggio Calabria appears, and soon afterward, almost as an afterthought, a smaller one announces the turnoff for San Marzano. Immediately, I plunge into a succession of towns, each one indistinguishable from the next and all bearing arrows pointing to my destination. "As soon as you get off the highway and head for San Marzano, you notice something strange," Nick had told me. "You say 'What's going on?' Then you notice the fields with fruits and vegetables. You see the soil and it's saying, 'Look at me. Look how rich I am!'"

Does the soil speak to me? Yes and no. I'd pictured great tracts of farmland bursting with perfect produce. Instead, there are plots of every size in every possible place—in front yards, abutting gas stations, along the edges of the road. The vegetation is rampant, elbows flying—watch out, here I come! Just like the drivers in San Marzano. There are hardly any signs, no working traffic lights, nobody stops. Except me. Then everybody honks as if I'm the crazy one. At 8 p.m., the streets are full of people. Chairs are set inches from roaring motorbikes, and nobody seems to notice. Anarchy is in the drivers, the fields, the town—in the Italian blood. I know. I feel it myself.

As a child, Savino Zuottolo lugged fresh tomatoes from his father's small farm to local markets in nearby San Marzano. Now, as a partner in Punto Verde, a company that owns 4,500 hectares, at harvest time he ships 88,000 pounds of tomatoes daily to locations throughout Italy, Germany, and Great Britain. "Three years ago, when I was visiting Savino in Italy, we exchanged ideas," Nick had told me. "Savino had the best tomatoes in the whole area at a great price. He said he would like to come to the U.S." Now, from the Albergo Nappo, on the outskirts of San Marzano, I place a call to Savino's office. The word americano gets the message across, and an hour later Savino, his partner Nicola Coppola, and I are engaged in a Marx Brothers routine of mutual incomprehension. Ultimately, we agree that Savino and an interpreter will pick me up at ten o'clock the next morning.

At 10:30 a.m., I am sitting on the hotel steps when Nicola pulls up. We walk across the street for a caffè macchiato—two sugars, a dash of frothed milk, and a shot of pure caffeine. Nicola, friendly and outgoing, is simply dressed, unshaven, rugged. The tiny demitasse almost disappears in his powerful hand. As he chats with the local men, some of whom are farmers, I can picture him striding through fields of tomatoes, a true man of the soil. When we leave, I notice that his little red car is an Alfa Romeo.

Inside a warehouse in San Marzano, workers are preparing vegetables for shipping. A woman chops the outer leaves from heads of lettuce and tosses them into a tub of water. Gialletto di Sicilia melons, which look like bright yellow footballs, fill metal bins. Crescenzo Zuottolo, a thinner, more carefree version of his older brother, helps two young women sort a pile of peppers twice the size of any I've ever seen. "Wait till you see them," Nick had prepared me. "They look like they come from another planet." I'm called into the office. Savino and the interpreter have arrived. Anna Pina Franza is a blond high school English teacher who sounds like Sophia Loren. She accompanies me to the rear of the warehouse, where deep red plum tomatoes are being boxed. Now can I find out why the san marzano is the best in the world for making sauce? I wonder. I ask Anna, who asks Crescenzo and translates his reply: "It has less sugar."

An empirical demonstration awaits. Several newly washed roma variety tomatoes are lying next to some just-picked san marzanos. The difference in appearance is striking. The san marzanos are thin and pointed. (Scrawny would be the most appropriate word.) The romas are plump and glowing with health. I try a roma first, and find it mild, juicy, and very pleasant, albeit a bit bland. In contrast, the san marzano is meatier and drier, with a much stronger, much better taste. And...it is less sweet! "I told you," says Anna. "It's not like candy or cake. In the san marzano tomato, less is more."

The Romano canning factory is state-of-the-art and smells like tomato juice. Savino is negotiating with the owners to package his san marzanos, and he wants me to see how a modern cannery operates. In a white lab coat, I follow two chemists through a maze of conveyor belts. Thousands of tomatoes are being ferried, analyzed, sorted, washed, scalded, peeled, and packed into cans, which are then sterilized and capped. Adorned with colorful labels, the cans rise in silver phalanxes to the ceiling.

It's all quite fascinating, but I'm much more comfortable when we leave this antiseptic environment, pick up Giacomo Mura (one of the farmers who supplies Savino with tomatoes), and drive out of town to his fields. There, row upon row of head-high san marzano tomato plants are growing so thickly that it is impossible to see where one ends and another begins. Trained on wires supported by wooden stakes, the bushes bear their fruit in hefty clusters. Some plants are so heavily laden that they have snapped their stakes like matchsticks.

Up and down the rows we walk, Giacomo stopping to point out particularly abundant yields. Now, the soil speaks to me—and I'm at a loss for words. I can only shake my head in wonder. As we return to the car, a worker with a bunch of grapes greets us and passes them around. The man shows me his hands, stained black as if by a permanent tattoo. "It's from picking tomatoes," he tells me. "The juice from the stems. Hard work," he gestures with a grin and waves us on our way. The fresh tomatoes I've seen in these fields will be shipped to supermarkets throughout Italy—in Rome, Ancona, Florence, and beyond.

This year, Savino's La Bella San Marzano brand of canned san marzanos (whose label bears san marzano–shaped tomatoes accompanying a ripe, beaming, and bosomy maiden, her lips and fingertips lacquered red like the san marzanos in her golden crown) are being shipped in limited quantities to the United States, among other places, where they're available in specialty stores on the East Coast. Then, as Savino comments while driving me back to the hotel, who knows? Nicola may be able to purchase another Alfa Romeo. As for me, if someone should ask how I came to write a story about a tomato, I'll simply say, "My barber made me do it."