I had been taken to this field, in the Aragon region of northeastern Spain, by veteran saffron farmer Indalecio Gomez to witness the harvest of this precious commodity—a process unchanged for centuries. For two to three weeks each October, the saffron harvest consumes the lives of Spanish growers and their families—Spain has long been an important producer of the spice—as they race to strip their small fields.

Gomez held one of the blossoms in his hand. The fall-flowering saffron crocus (Crocus sativus) is as delicate as the spring crocus, to which it is closely related. Six lilac-colored petals form a goblet shape on its thin stem. Gomez gently opened the petals to show me the treasure inside—three crimson, threadlike stigmas in the center of the blossom that will be transformed into the costliest spice in the world.

As I watched the pickers moving across the field, baskets hooked to their belts, I had the strange feeling of being in another time. A man driving a horse-drawn wagon waved as he rattled down the lane. It might have been the 19th century.

This was not my first visit to the saffron fields of Spain. I fell under saffron's spell half a dozen years ago. It was then, while staying with a friend in the Spanish wine region of Rioja, that I met my friend's mother, Maria Gomez. The Gomez family has cultivated saffron for many generations in the town of Bañon, 75 miles south of Zaragoza in the Aragonese province of Teruel, and she talked about the spice, and about the traditions of its harvesting and processing, with such passion that I knew I had to see it for myself. Since then, I've traveled repeatedly through Spain's main saffron-producing provinces, from Teruel in the northeast, to Cuenca, Albacete, and Ciudad Real in the Castilla-La Mancha region, in central Spain.

On one occasion, I watched the monda—in which the damp red stigmas are painstakingly hand-stripped from the flowers—in the sleepy La Mancha town of Barrax. There, inside a former restaurant, three generations of mothers and daughters were sitting at a flower-covered table, their hands moving in a blur. On the floor around them were thousands of petals. The room was filled with a subtle, exquisite aroma recalling freesia and vanilla, an aroma giving no hint of the complex flavor of the spice itself, which is at once floral and pleasantly bitter, reminiscent of tobacco, hay, and cedar, with nuances of pepper, citrus seed, and menthol.

A handsome and somewhat fierce-looking woman in her seventies, dressed entirely in black, talked tenderly to her teenage granddaughter as she worked. With one hand, she picked up a flower and separated the petals; with the other, she stripped the threads from the yellow style to which they were attached. (She took care not to include the styles themselves, which would diminish the saffron's value.) The threads were then tossed onto a tin plate, and the spent flower dropped to the floor. The old woman stripped each blossom in less than four seconds. An experienced picker, she could strip about 1,100 flowers in an hour, producing about a quarter of an ounce of saffron; a day's work would yield two to three ounces of the spice, an amount worth as much as $850 on the retail market.

"How long will you work today?" I asked the women, who talked and sang songs as they labored. They laughed shyly, shrugging and pointing to several baskets of flowers still waiting in the corner. "Till it's done," said one. "Till it's done."

There is no machine that can strip the saffron flowers, just as there is no mechanical way to speed their harvest. Hardworking hands must process about 70,000 flowers to obtain a pound of finished saffron. Hence the spice's astronomical price—roughly $450 a pound wholesale and as much as $4,500 retail for saffron of the highest quality. For first-time buyers of saffron in the supermarket, knowing this might lessen the shock of paying about $5 for half a gram, the yield of about 80 hand-picked flowers.

Saffron is almost as old as civilization, and its influence on culinary history has been vast and almost mythic. It was apparently first cultivated in Persia and Asia Minor in ancient times, and is praised in the Bible's "Song of Solomon," in Homer's Iliad, in Virgil's poems, in the Papyrus Ebers (an important ancient Egyptian medical text), and in the first-century cookbook of Apicius. Saffron was introduced to Spain by the Moors in the tenth century. (Its name derives from an Arabic word of unknown origin, za'faran.)

During the Middle Ages, the use of saffron in cooking spread throughout Europe. Saffron is the defining ingredient in some of the Continent's most celebrated dishes—Spain's paella, the bouillabaisse of Provence, risotto milanese—and is essential to the cuisines of India, Morocco, and Iran. It has also been coveted throughout history as a dye, a perfume, and a medicine.

As with any expensive commodity, saffron has inspired fraud. Unscrupulous merchants have coated it with molasses, honey, or wax to add weight. Faux saffron has been devised from red-dyed corn silk, fine shreds of red wood, and the petals of safflower, arnica, and marigold. Brick powder, metal oxides, and lead powders have been used to mimic ground saffron, as has turmeric. In addition, importers say that inferior-grade saffron is often passed off as the highest quality, due in part to blatant deception by some unethical Spanish exporters.

Though some sources estimate that as much as 60 percent of the world's saffron is produced in Spain, the Spanish government now puts the figure at 15 to 20 percent. The rest comes from Iran, India, and Morocco, with some small-scale production in Crete, France, Turkey, Italy, and elsewhere. But at least 90 perent of the saffron sold in America is Spanish.

The La Mancha region, a vast, spare plateau beginning about 35 miles south of Madrid, is said to produce the best saffron of all. Here, the landscape resembles an eccentric mix of the American West and poetic Spanish farmland. The region's windmill-dotted fields and its vineyards and olive groves evoke the legend of Don Quixote; its arid plains and low mesas are straight out of a Louis L'Amour novel. The saffron fields emanate from scruffy Manchego farming villages like Membrilla, La Solana, San Pedro, Barrax, and Munera. A festival honoring the saffron rose, as the flower is known locally, is held in the village of Consuegra around the last Sunday in October. Otherwise, the harvest is a quiet affair, often going unnoticed by the casual traveler.

It was not in La Mancha but in Aragon, in Bañon, that I really saw saffron up close—thanks to Maria Gomez and Indalecio Gomez, Maria's brother. The siblings share a direct and unaffected manner. Maria Gomez, strong and compact, wears the plain dress and cardigan sweater typical of the country women you see in local markets all over Spain. Indalecio Gomez is a robust, balding man, his face weathered from years of working outdoors. Gomez is wise in the ways of his world, knowing things like where to find the delicious seta de cardo mushrooms that were invisible to my eye, and how to rid the saffron fields of rodents with a bellowslike contraption that forces smoke into their burrows.

When I asked how long the family had been in Bañon, Gomez replied simply, "Forever"—with a sweeping gesture to indicate centuries past. This ancient village, which looks like a Cubist painting, all ochre and terra-cotta rectangles, predates the Moors.

No farmer in this region grows just saffron. Gomez cultivates grains and raises pigs on his farm, and planted saffron crocuses to provide extra income. A farmer will tend a plot of saffron only as large as he and his family can harvest. One hectare (about two and a half acres) will yield from six to 12 pounds of saffron (depending on irrigation), and might require 15 or 20 people to harvest. Some saffron fields are as small as an eighth of an acre.

Once the long labor of stripping the flowers is finished, the threads must be carefully and quickly dried to develop their flavor, and to remove moisture, which can cause the saffron to rot. If this is done incorrectly, hundreds of dollars in saffron can be destroyed in an instant. The wet threads are placed in a drum-shaped sieve over a heat source, most often the embers of a wood fire, and watched carefully. Farmers often develop their own refinements, like the ingenious one Gomez has devised: He dries his saffron by leaving the sieve overnight on the floor of his house, on tiles heated by a "Roman oven," a wood-fired furnace built into the foundation. In another household, I saw saffron placed in a metal plate on a burner over a low flame on the kitchen's small gas stove. On the next burner simmered a stew of shrimp, clams, garlic, and tomatoes.

The threads will lose about 80 percent of their weight in the drying process. Five pounds of fresh stigmas will yield one pound dried, for which a successful farmer will receive 41,000 to 50,000 pesetas (between $340 and $415). To weigh the saffron, most farmers still use homemade scales—roughly crafted tin plates hanging from iron chains attached to a crude crosspiece. Weights are made of hand-forged iron, often stamped with the family crest or another personal symbol.

Farmers are paid in cash or scrip. In the latter case, an agent issues a farmer a receipt that can be redeemed at the local bank. The informality of this arrangement is indicative of the degree of trust that exists between the buyers, the growers, and the banks.

Not all farmers necessarily sell their saffron as soon as it is harvested. It can be kept for years if stored in an airtight vessel away from light and moisture. Some stash it away for emergencies, or until they can get a better price. "It is like having a savings account," Maria Gomez explained to me, adding that parents often leave saffron to their children in their wills. One woman, seemingly of little means, surprised the town by leaving her children more than 30 pounds of saffron, accumulated over the years. Farmers often hide saffron among their good clothes, which are then permeated with its aroma. The churches are filled with the smell of saffron when everyone wears his Sunday best.

Saffron production in Spain has declined by 50 percent over the last two decades—although it seems to have stabilized in La Mancha. As the cost of living has risen in Spain, some farmers, especially the younger ones, consider it too much hard work for too little profit. And farmers face increasing competition from other saffron-producing countries, especially Iran and India, where labor costs are lower.

To illustrate the frustrations a saffron farmer can encounter, Indalecio Gomez took me early one morning to meet Manuel Martin Villalba. Villalba, who has been cultivating saffron for three decades, was picking flowers with his son Juan Jose in his field on the outskirts of the Aragonese village of Monreal del Campo. He was clearly disheartened as he gestured sadly at the field dotted sparsely with saffron flowers. This would be his last harvest. He could earn only half of what he made 25 years ago, he said, due to competition from La Mancha and to severe weather, which had stunted his plants.

He pulled one up by the roots. "Normally," he said, "a mature plant like this would be large and have three to five flowers. This year, all the plants were small, with only one flower growing out of each root system. We had no rain in March, when it is critical. Then there were months of drought, followed by hard rains all fall. We knew it would be a disaster."

Despite the hardships of the saffron farmer's life, Villalba obviously regretted that this was his final harvest. He spoke of the pleasure he had taken through the years in a way of life that has been handed down from father to son for generations. He had hoped to pass it on to his own son.

We helped Villalba pick the remaining flowers in the field. He poured them into a cardboard box, which he gave to me. "You will have some Teruel saffron to take home to America," he said.

Later, we stripped the blossoms in Maria Gomez's tiny dining room. Her brother's wife, Esperanza Zorraquino, her hands thickly callused from farm work, nimbly stripped five flowers to my one.