Experts can size up a wine long before it goes into the bottle. Lettie Teague picks up some pointers during a barrel tasting with winemaker Helen Turley.

Like most reasonably cute but not beautiful children who evolved into stereotypically awkward adolescents and emerged as reputable adults, I've wondered, from time to time, how I turned out the way I did. Immersing myself in studies of developmental theorists got me nowhere. Nor did talking to my mother ("You were always fine, dear").

Then, Helen Turley came into my life and made it all clear: The evolution of a human being and a wine are pretty much preordained. For a wine, it begins in the barrel, the cradle of Cabernet, Chardonnay and other great wines.

Barrel tasting calls for sampling a wine at various stages of its very early life, well before it is bottled, and making a judgment as to its future development and eventual worth. It's something that wine merchants and critics do on a regular basis, projecting to the wine-buying public how they believe the final product will turn out.

Barrel tasting has become increasingly important in recent years as more and more wines, not just Bordeaux, are sold en primeur, as futures. (Buying futures means you agree to pay a certain price for a wine before it is bottled and shipped, sometimes several years in advance.) The evaluations of these wines, and the sometimes spectacular sums invested in them, are almost entirely based on barrel-tasting reports. In fact, barrel fever has become so intense that some restaurants have made barrel tastings featured attractions. Last spring wine merchant Kermit Lynch teamed up with Oliveto restaurant in Oakland, California, to offer a series of barrel-tasting dinners. A salesman for Kermit Lynch, Michael Butler, said the guests appreciated getting a preview of what the wines would eventually be like and particularly enjoyed penetrating the elite world of barrel tasting, traditionally a privilege reserved for professionals.

As a New York­based wine editor and writer, I live several thousand miles from where most great wines age in barrel. If I wanted to talk (and taste) with a true "barreliste," I'd have to travel. I decided to visit Helen Turley in Sonoma. Turley is not only one of the best winemakers around but a self-confessed barrel fanatic--or, as she likes to say, "the poster girl for French-oak barrels." Turley, whose commanding profile has been praised almost as often as her winemaking skills, is a woman of strong convictions and unvarnished opinions. I knew she'd have something incisive to say and, of course, some amazing wines to taste.

Famous for her tender barrel techniques--the critic Robert M. Parker, Jr., has said she "treats her wines in barrel as if they were infants"--Turley makes highly sought-after, tightly allocated wines under her own label, Marcassin, and also for wineries such as Martinelli and Bryant Family Vineyard. Turley relies on labor-intensive vineyard management (densely planted vines, extraordinarily low yields) and painstaking winemaking techniques (wild-yeast fermentations, weekly stirring of the lees, etc.). She barrel-tastes her wines hundreds of times to check on their progress, although she also barrel-listens; during fermentation, she says, "Chardonnay crackles, then sounds like bees." She even barrel-sniffs. According to Julie Martinelli, "Helen had all the barrels brought down to one level so that she could smell them more easily."

I arrived in Sonoma on a brilliantly sunny morning in late spring (the best time to barrel-taste). Before we began, Turley and I talked a little barrel-tasting theory. First, I wanted to know what Turley thought someone could possibly get out of barrel-tasting a wine just once (which is how most critics come up with their evaluations). Turley, true to form, didn't mince her words: "Tasting a barrel sample once is not a valid methodology for judging a wine." What, if anything, did she think might be detected from a single tasting? Turley considered. "If someone is knowledgeable about wine, whether they've tasted from barrel much or not, they can assess smoothness, depth and flavor. Smoothness is something that even neophytes can taste. When they taste a wine they'll say, 'Oh, it's so smooth!'" But a single sample certainly wouldn't enable its taster to declare precisely how and when a wine will mature.

With that, we began walking toward the barrel room (in fact, two red barns, one small, one large) shared by Marcassin and Martinelli. En route, I mentally excised the word smooth forever from my vocabulary. Turley announced that we'd start with the 2000 Marcassin Chardonnays, scheduled to be released in 2003--wines made in such limited quantities that the winery's mailing-list customers will likely be outraged to read that even the smallest sample was offered. She pulled up a sizable tasting sample for each of us with her glass pipette. None of the four had much in the way of a bouquet--true of most wines in barrel. Turley explained, "Chardonnay and Pinot Noir are very reduced; they have almost no exposure to air in the barrel. If you introduce air to the wines in barrel, you'll take away the aromatics in bottle." In the mouth, it was another story altogether. The purity and power of the flavors--honeysuckle, citrus and minerals--were nearly overwhelming. The textures of the wines were equally remarkable: Each offered mouthfuls of lush, layered fruit and mile-long finishes. These wines were so gorgeous, so potent yet subtle, that even the most confirmed Chardonnay hater (which I'm not) couldn't help but be converted on the spot.

We moved to the second red barn to begin tasting the Marcassin and Martinelli Pinot Noirs. Turley noted, "Pinot Noirs can be very different one barrel to the next; Chardonnay is more consistent." But she couldn't help marveling, like any fond mother, at "how well behaved" these Pinots were. This proved to be a wild understatement on her part. These wines were nothing short of spectacular--the Blue Slide Ridge Vineyard Pinots in particular (made under both the Marcassin and Martinelli labels). These wines were so unbelievably rich, so incredibly concentrated, so fully evolved, their fruit and tannins so perfectly synthesized, it was hard to believe they weren't hours away from bottling. As I stood gaping, glass in hand, Turley smiled in modest acknowledgment. "These wines tasted this way when they were just juice."

In other words, this was no barrel-born phenomenon. As Turley explained, these wines were as remarkable now as they were at the beginning--even before the grapes were picked. Or, as Turley says, all of her work in the vineyard enables her to know "just from tasting the juice of the grapes what kind of wine we'll have"--long before it ever reaches the barrel. Had there ever been an exception? I wondered. Had Turley ever had a wine that was maybe a little less promising in barrel--a bit awkward, ungainly even--turn out to be great in bottle? (I was thinking Bill Gates in high school and, to a lesser extent, me.) Turley's reply was swift and certain: "No." To Turley, a beautiful wine in bottle is beautiful in barrel. Beautiful, in other words, from beginning to end.

The world of great wine, it seems, is even less forgiving than high school.