A fellow came up to me the other day and said, "How long do you think such-and-such wine will live?"

My initial impulse was to reply, "How the hell do I know?" But that, of course, is hardly what he wanted to hear.

So I blathered on about cellaring conditions (cold slows maturation), cultural differences in taste (the French and Italians prefer younger wines while the English like their wines well-aged) and, finally, the sheer impossibility of predicting the life trajectory of any wine.

I should have saved my breath. "I don't think the wine has structure," he said, full of self-assurance. That, he asserted, was the predictor of longevity.

Where does this stuff come from? And, more important, why does it persist? It's astonishing how certain beliefs are the undead of wine, forever resurrected and roaming about. For example:

The Structure Myth. Structure is no more a predictor of a wine's future "career success" than your fourth grade attendance record. So why did this business about "structure" become such a devoutly held article of truth?

The myth of structure derives from a long-held and mistaken notion about tannins. Time was, wine drinkers looked at tannin levels in wines, especially red Bordeaux, as a marker of longevity.

A wine without a sufficiency of tannins was thought to lack the necessary "carpentry”; it lacked structure. Wines that could age needed musculature; short-lived wines were akin to jellyfish. (You needn't be a Freudian to assess George Saintsbury's famous description in his Notes on a Cellar-Book of a 40-year-old Hermitage, made from tannin-rich Syrah, as "the manliest French wine I ever drank.")

Effectively, the business about structure came from a Bordeaux-centric view of wine, one that persisted into the 1980s. You might well ask, "What about all those white Burgundies and German Rieslings that age successfully for decades?" Good point. They were conveniently ignored as outliers. Real wine was red, and needed "structure" in order to age for decades.

We know better today, of course. Indeed, the Bordelais themselves long ago dispensed with "structure" as a guiding measure, instructed by no less influential a figure than Emile Peynaud (1912–2004), the university professor and ubiquitous Bordeaux winemaking consultant who single-handedly reshaped how Bordeaux châteaus made their wines.

The breakthrough moment was the 1982 vintage, a rich, ripe year that traditionalists harrumphed lacked "structure." Have you had an '82 red Bordeaux lately? Thirty years have now passed and the '82 red Bordeaux are sailing along just fine, thank you.

Wines age successfully thanks to a confluence of forces involving acidity, phenolic ripeness, pH and that mysterious thing, the wine version of dark matter, called "balance." Some wines, such as cru Beaujolais from great vintages, reach magnificent heights after decades of aging with nary a tannin to be found. Ditto for Barbera, which is one of nature's least tannic red wine grapes.

Forget "structure" in evaluating a wine's capacity to age to glory. It's a myth.

The Money Myth. This one will never die, I know. But still, it's got to be said: There's very little correlation anymore between the cost of a wine and its intrinsic quality. And once beyond, oh, $30 a bottle, there's absolutely no correlation whatsoever.

It's irresistible to conclude that something more expensive is always going to be better than something cheaper. As Thomas Paine put it, “That which we obtain too easily, we esteem lightly. It is dearness which gives everything its value.”

So, OK, I accept that this myth will persist. But I have to add that never in the history of wine has it been less true than today. Winemakers everywhere have advanced scientific educations, equally advanced modern equipment and high ambitions toward quality. The result has been an unprecedented explosion in superb wines from everywhere.

Inevitably, some wines will be better than others. And some wine districts are still improving, with yet more accomplishment to come. But the fact is—and it is a fact—that the old wine aristocracy has been supplanted today by a new wine meritocracy. If you miss this critical fact, then you've missed the most important feature of 21st century wine.

Thanks to this revolution, price has lost potency as a predictor of quality. Simply put, many of today's most interesting, most invigorating—dare I say "best"?—wines are not necessarily high-priced. Many superb wines from Spain, Portugal, Italy, France, Oregon, Hungary, New Zealand, Australia and, yes, even California, sell for $20 to $40 a bottle. That may not quite be pocket change. But it's not expensive, either—especially given the quality and originality on offer.

That price tags now tell us anything worthwhile about wine quality is a myth.

The Humidity Myth. I've banged on about this for decades, so I'll be brief. You've all read, over and over again, about how your wines should be kept in a cellar with a certain amount of humidity. The figure cited is anywhere from 70 percent to 95 percent humidity. The reason, so-called, is that you need to keep the cork moist.

This is nonsense. Think about it. Your wine is encased in a glass bottle. It's sealed by a tightly compressed cork, one end of which has a dime-sized exposure to air. (Actually, that’s not even fully exposed, as most corks are covered by a capsule.) The other end of the cork is kept outright wet by the wine if the bottle is stored horizontally.

How much humidity, if any, is going to penetrate the cork, which is already very tightly compressed? Virtually none. And no scientific study, to my knowledge, has demonstrated otherwise.

So why does this myth persist? Fear, mostly. And history. Wine used to be shipped and held in wooden barrels or casks, even in private homes and certainly in restaurants. Private consumers bottled their own wines when they saw fit.

A wood barrel, unlike glass, is porous. When wine is held in a barrel you most definitely want a high humidity, which helps keep the staves tight and reduces the amount of evaporation through the pores of the wood.

In a conventional winery cellar, about 10 percent of the contents of a barrel is lost through evaporation every year. This is why wineries like to have caves, which have an ultrahigh, 95 percent humidity. In Napa and Sonoma, which have high-priced wines, the cost of constructing a cave pays for itself in about seven years from "saved" wine.

Simply put, what's good for wineries and their wood barrels makes absolutely no sense for home cellars with their tightly corked glass bottles.

The need for humidity in home wine cellars is a myth.