There is a saying in history, with the obvious spillover into the wine world, that “in wine, there is the truth.” The Latin expression is in vino veritas.

Pliny the Elder of Roman times is credited with the saying, but it predates him back to the Grecian era, where Alcaeus, a poet, first expressed the thought that government councils could do their work with greater efficiency and accuracy while drinking wine. The concept must have been universally agreed to, as the use of wine during official and recorded governmental meetings was widespread and accepted. Do ya’ think they were on to something that we’ve lost?

A different sort of challenge exists for us modern imbibers and it has nothing to do with appeasing an increasingly restless Roman rabble, nor appealing to the gods of Olympus to assure that the noble experiment with democracy goes well.

The “challenge” we are facing, almost continually, is the wine-by-the-glass programs at just about every restaurant, bar, and particularly, wine bars. While I am completely supportive and even enamored with programs that serve fine wines by the glass, all is not well in just-one-glass-of-wine land.

As we all know, air is necessary to help a wine “open up” and further develop after the stopper has been removed from a bottle. That’s why we decant, swirl and do what has to be done to maximize immediate exposure to air, which the wine has been denied for at least several years.

On the other hand, long-term exposure to air deteriorates the wine. The wine soon becomes uneven, exposing unpleasant odors in the bouquet and pushing some mouth-feel aspects, such as alcohol or tannins, up into the unbalanced range of flavors.

When a wine has been opened, and maybe a quarter of the bottle has been removed with glasses that have been sold, stoppered for the night, opened again the next day and a few more glasses removed, then stoppered for the second night, and finally finished on the third day after initial opening, you have, in the end, a very fatigued wine. Maybe even one that is not “right.”

The real issue here is not whether the wine is “good” or “bad.” The wine after being open a while under any conditions does not taste like it should. And no amount of rubber stoppers and pumping air is going to keep the wine in fine order. Many wine bars just stick a cork back in the wine at closing time. That is the worst way to try and keep a wine fresh. And the bar people know it will not work.

Others do the rubber stopper and pump-the-air-out exercise. Then they sit the bottle on the back bar. Also no good. If they would put the wine in the refrigerator overnight, both reds and whites, that would help a little bit more.

Some bars use the inert gas method, pushing air out of the bottle and replacing it with Argon or Nitrogen, both in widespread use in the service and winemaking industries. This is the way for professionals to go. Still not perfect, but better than just about anything else.

What is pretty amazing to me, however, is why some bar owners just don’t toss the opened wine down the sink at the end of the evening, or simply offer to sell it to the last customers before closing for half of the cost it usually is. I’m talking here when a bottle is more than half-empty (or half-full, depending on your stance on the age-old question). Why would a bar proprietor keep the product? They have already recouped costs, and why serve an inferior product to customers at any time, particularly the next day?

Here’s what I do when faced with this situation: I tell the bar person that what has been poured into my glass has been open too long. Most of the time, they will willingly open another bottle. But if they do not, I tell them I will pay for the entire remainder of the old bottle and for the entire new bottle, if the wine tastes the same from both bottles. I even let them have the first taste from the freshly-opened bottle and compare it to the old bottle.

I have yet to have to pay for both bottles.

You can do this too, if it is worth the trouble to you, and if you have confidence that the contents of a bottle that has been open for awhile are not in good order. If you are not certain of your position, or if you are unfamiliar with the wine and just don’t know what the hell it should taste like in the first place, don’t go this route. It could get unnecessarily expensive.

But the point is this; any wine that is poured by the glass in 95% of serving establishments is just not that expensive at the wholesale level. You are a customer. Is it worth even $15 out of their pocket not to make you happy with your visit?

Also keep in mind that there is always the possibility that the bottle that has set on the back of the bar overnight was not that good in the first place. Most bar personnel do not know a wine that is flawed, or even corked. I have almost never seen a bar server check out a bottle of wine by smelling it and even tasting it after opening.

Keeping an already flawed bottle of wine another 24 hours is not going to make it better. It will, in fact, go quite the other way. Not a good thing.

You are the customer and you deserve a product that is in first-rate condition. Previously opened, day-old wine simply, as a rule, can’t meet that test.

Often while tasting wine that is in less than pristine condition, I wish I had the winemaker with me. Consider that great scene in “Annie Hall,” when Woody Allen and Dianne Keaton are in a movie-ticket line, and the guy in front of them is expounding foolishly about some aspect of modern mass communications philosophy.

Woody had heard all of the drivel he could stand, and, from the background, brought Marshall McLuhan, noted sociologist and author of the book, “The Medium Is the Message,” over to straighten the guy out. Speaking to the camera, Allen asked, don’t we all wish it was that easy to deal with such matters?

Yes, Woody. Yes, I do.