With the recent purchase of a plot of vines next to a Gothic cathedral in the old German city of Worms, the Valckenberg wine firm is not merely tidying up some unfinished business. It's struggling to put a genie back in the bottle.

Since 1807, this family-run company has owned more than half of the so-called "Madonna vineyard," the cradle of Germany's best-known wine, Liebfraumilch. With the additional 19 acres, it now owns 90 percent of the vineyard, where Valckenberg produced the first Liebfraumilch well over a century ago. However, the Liebfraumilch genie long ago escaped the confines of that single plot of land.

Today, "Liebfraumilch" is little more than a catchall name for an inexpensive, vaguely sweet German regional wine. Like "Chablis," which once referred only to wine from the Chablis district in northern France, Liebfraumilch now means practically nothing. However, it is big business, representing more than half of Germany's total wine exports. The best-known brand, Sichel's Blue Nun, is the biggest-selling German wine in the United States, and is among the top 20 imports.

While these and other Liebfraumilchs are not necessarily bad wines, they bear faint resemblance to the original article made in Martin Luther's back yard. But at least Valckenberg's purchase reminds us of the wine's distinguished past.

The Madonna vineyard is located beside the Gothic Liebfrauenkirche ("Church of Our Dear Lady") monastery, which was founded by Capuchin monks in 1296. The monks' wine soon developed a following among thirsty pilgrims, who were said to exclaim that it tasted as gentle as "the milk of Our Dear Lady." Thus, allegedly, was born the phrase "Liebfrauenmilch," soon truncated to its current form. Lest anyone miss the Madonna connection, an aging sandstone statue of the Virgin and Child sits against an old stone wall overlooking the vineyard.

After the French Revolution, Napoleon's troops occupied all of Germany west of the Rhine. As in Burgundy, Church vineyards were seized and put up for auction. In 1808, Valckenberg's founder, Peter Joseph Valckenberg, by then a successful wine merchant, purchased the largest part of the Madonna vineyard.

While Napoleon was meeting his Waterloo, P. J. Valckenberg was building his fortune. Liebfraumilch became a hot item in England -- so popular, in fact, that soon Valckenberg was clearly selling a lot more Liebfraumilch than could possibly have been produced from the Madonna vineyard. Whether he knew it or not, Valckenberg had invented the first wine "brand." In other words, Liebfraumilch was selling based on the name on the label rather than by the particular vineyard or grape variety. Soon there were many wines competing with Valckenberg's, some good, some mediocre and some awful, but all of them called Liebfraumilch.

In 1908, a last chance came to return the genie to the original vessel. A new German wine law similar to the French appellation controllee law went into effect. It could have reserved the name Liebfraumilch to the Madonna vineyard. However, along with the other owners of the Madonna vineyard, Valckenberg had too much of a financial stake in the huge generic Liebfraumilch category to seek protection. Instead, the new law stipulated that wine from the Madonna vineyard would be denominated "Liebfrauenstift." Later changes denominated the wine as "Liebfrauenstift-Kirchenstuck."

Valckenberg exports small quantities of Kabinett, Spatlese and other Liebfrauenstift-Kirchenstuck wines and will soon inaugurate an independent estate winery that will produce wines exclusively from the Madonna vineyard. Valckenberg also makes a generic Liebfraumilch that it sells under its Madonna brand. However, the real story of Liebfraumilch today is Sichel's Blue Nun. Though not much respected among wine connoisseurs, it is consistent and reliable, and sells well in supermarkets and most ordinary wine and liquor outlets across the country.

The important thing is that Blue Nun is getting better. With so many Liebfraumilchs out there, Blue Nun had to improve the product to keep its customers. Blue Nun's grapes -- Riesling, Muller-Thurgau and Silvaner -- come only from the Rheinpfalz and the Rheinhessen regions, where the Liebfrauenstift-Kirchenstuck vineyard is located. To add body, and definition, Blue Nun now blends in Kabinett and Spatlese wines, which are at a higher official classification than required for Liebfraumilch under German wine law.

These changes represent a turning point in the long, shamelessly commercial history of Liebfraumilch. They also say something good about today's wine consumers: In the 1800s, the English were willing to accept an increasingly poor wine as long as it was labeled Liebfraumilch. Today, American consumers are willing to accept a Liebfraumilch only as long as it's getting better.

The genie may not be back in the bottle. But at least it's headed in the right direction.