Good wines are never just one thing. They are instead an expression of two parts, grape and place, with the help of a third, producer. If each of these three things is well suited to the others and in proper balance, then they combine to reveal a fourth, terroir, which transcends the other three. That, above all, is the elusive quality we strive to find here at Wine School.

We believe that terroir is what separates interesting, distinctive wines from the merely enjoyable and the mundane. In the practical world of Wine School, in which we drink wines together and discuss them through the Food section website, it’s fascinating to actually taste the quality that we spend so much time discussing. Conversely, it’s sometimes just as illuminating to examine its absence.

That was the issue in question for me after I drank the three Irpinia aglianicos we’ve been focused on for the last month. Each of the wines certainly qualified as enjoyable, though each was very different. But did they offer any more than that?

The three wines I had recommended were the 2013 Quattro Confini from Benito Ferrara, the 2010 Cinque Querce from Salvatore Molettieri and the 2010 Gioviano from Il Cancelliere. Many readers were not able to find these wines, but they chose good substitutes.

Aglianico, as I’ve said, is perhaps the least known of Italy’s great red grapes, at least in the United States. It has not commanded the respect of the nebbiolo wines of the Piedmont region or the sangioveses of Tuscany, nor has it had the recent vogue of the nerello mascalese wines of Sicily. This partly explains why it’s a challenge for Americans to find good aglianicos.

Yet aglianicos meet the criteria for greatness. They can be both powerful and subtle, they can age beautifully, and they can be both soulful and contemplative, especially when grown in the best places and produced by careful, respectful hands.

Where are the best places? Aglianico seems to thrive in volcanic soils, especially at higher elevations on hillsides that also have some limestone mixed in. The Taurasi zone, in the high hills near Avellino in eastern Campania, is the most famous region. Taburno nearby can also produce superb wines, while the aglianicos from Mount Vulture, an extinct volcano in Basilicata, can be as good as any.

When produced in other areas, like the coastal Paestum region of southern Campania, as James Carman of Alexandria, Virginia, pointed out, aglianicos can be very different.

The best wines from any of these places share a density of flavors, along with high acidity and powerful tannins, that allow them to age for years. Not so long ago, I drank a 1968 Taurasi Radici from Mastroberardino, the pioneering Campania producer, and it was complex yet youthful, with many years to go. But in their youth, these wines can be tough and tannic, a little like Barolos and Barbarescos.

Looking for wines that would be easier to drink young, I chose Irpinia aglianicos, which have the same relationship to Taurasi and Taburno as Langhe nebbiolos have to Barolo and Barbaresco. They are from the same general area but tend to be softer and more accessible.

Not surprisingly, the three wines I chose did not have the depth or complexity that is typical of better aglianicos, nor did they have the structure to age for particularly long, even though two of the wines were already five years old.

Even lesser wines can demonstrate the characteristics of terroir. The village wines of Burgundy are a perfect example, though, to be fair, few areas in the world can even approach Burgundy for the organization and codification of its region.

The Benito Ferrara, I thought, was the least of these three bottles, and nobody disagreed. Dan Barron of New York, who’s enjoyed aglianicos before, called it “the lightest-bodied of any aglianico I’ve tried.” It was simply an easygoing, unchallenging wine, soft and almost velvety rather than rugged as I’d expect a young aglianico to be. On the palate, it was fruity rather than earthy, with flavors of red fruit and a touch of licorice.

It was a pleasant wine, but no more, intended for easy drinking. The grapes came from soils that were primarily clay and had little of the structural elements that often come from aglianico grown in soils with more limestone. And the wine was aged largely in steel tanks, which develops fruitiness rather than structure. Likable, yes. But terroir? No.

By contrast, much more was going on in the 2010 Cinque Querce from Salvatore Molettieri. These grapes were grown in soils with a limestone component, were macerated with the tannin-producing skins for an extended period compared with the Ferrara, and then aged in barrels for 16 months.

The wine was much more structured and complex, earthy and floral with a sarsaparilla-like herbal quality and a rough tannic rasp that gave this wine more texture and character. It’s not profound by any means, but it was an excellent entryway to the deep, concentrated Taurasis that Molettieri produces. Terroir? Indeed.

The 2010 Gioviano from Il Cancelliere was more in the vein of the Molettieri than the Ferrara. It was a big, powerful wine, made from grapes also grown in soils with limestone, macerated for even longer than the Molettieri and aged in barrels.

I liked the structure and depth of this wine, and its flavors of red fruit, flowers and licorice. It definitely benefited from decanting, opening up over several hours and especially after a day. But I felt it was a little high in alcohol at 15 percent. I could feel the burn in the back of my mouth. Yet the headiness did not obliterate the sense of place, which was apparent.

Some readers seemed to enjoy the Gioviano more than I did. Ali of New York, who shared a Wine School dinner with Dan Barron and their partners, called it a big hit, and Barron said it was “deep, dark and satisfying in a way the first two could not match.”

George Erdle of Charlotte, North Carolina, was also able to find all three wines. He liked the Ferrara on its own, but found it too light to go with flank steak. I’m not sure how he felt about the Molettieri, but the Gioviano, he said, was a perfect match with braised short rib and his dining group’s favorite wine with food.

Food was imperative, as it almost always is for good Italian reds. Seancpa of Pleasant Mount, Pennsylvania, drank a 2009 Taurasi, which he described, using a television reference that predates me, as “Gene Barry playing Bat Masterson,” meaning, “elegant, dapper, quietly confident but strong and fearsome.”

It was great with a lamb stew, he said. What about for sipping without food? For that, he said, “This wine was problematic for me: lots of tannin, almost a grittiness on the palate.”

Those soft, easy wines, like the Ferrara, are much better for idle sipping, or, as Anthony Esposito of New York suggested, for soaking slices of peaches for a day or two. Their reason for being is easy drinking, a legitimate commercial proposition. But wines that display terroir are something more. They express a sense of place and a culture, and their effect is transporting.