VINES tumble away to the Rhine below me. Above me, dry-stone terrace walls arrest the Gadarene rush to the churning brown water. A ruined castle - the schloss of the Schlossberg vineyard - stands sentry on the bank of the legendary river. Schlossberg marks the "corner" where the Rhine tacks north again to Cologne after flowing westward for 30km. The 90-degree bend in the river makes navigation treacherous; like the Lorelei Rock further north, the rapids of the Binger Loch have been the nemesis of careless mariners for centuries.
It is a turbulent morning on this exposed corner: a furious wind howls through the naked vines, thin sheets of rain drift horizontally and the Rhine is in flood. Were I a monk a millennium ago, I cannot imagine this inhospitable spot would have suggested itself to my pious mind as an ideal vineyard plot.
And yet those are the two things that define this region, the Rheingau: religion and wine. The religion I found early one Sunday morning on a slope above the village of Rudesheim. As I strolled through the vineyards, the Rhine below was shrouded in a gossamer veil of hazy fog. My destination was a convent built in the early 20th century, but with ancient roots - the Abtei St. Hildegard.
The 12th century nun, Hildegard of Bingen, was born in 1098 and founded her first convent in Bingen, across the Rhine from Rudesheim, in 1150. She achieved fame as a composer, a seer and even an early proto-feminist. In one of her texts on medicine, she observed that "a pure wine purifies the blood of the drinker…" Hildegard's compositions are still sung by the 50 or so Benedictine nuns in the convent church, situated in the Klosterberg vineyard (she is one of the earliest Western composers whose works survived). And they still make wine, but it was Sunday and the convent shop was closed.
A few kilometres further west, I called at the much older Cistercian monastery of Eberbach. Together with Hildegard's foundation, these were once two of the most august religious houses north of the Alps. Eberbach's last monks were swept away by the Napoleonic wars two centuries ago, but the 12th century monastic complex, including the venerable Hospitalkeller, has been remarkably well preserved (so well, indeed, that it was used to shoot Sean Connery's film version of Umberto Eco's The Name of the Rose). The monastery was founded in 1136 and was once one of the greatest vineyard owners in medieval Europe. Nowadays, Eberbach is the headquarters of the Hessische Staatsweinguter (or state winery of the German state of Hesse) and still a landmark in the history of viticulture in Germany - and Europe.
Another estate with holy roots is the famous Schloss Johannisberg. The castle's yellow facade dominates from a hill above the village of Johannisberg, between Geisenheim and Winkel. Legend has it that Charlemagne, while based at his castle at Ingelheim, noticed that the snow on this hill melted first and thought it would make a good spot for a vineyard. By 817AD, the existence of vineyards on this spot had been recorded and after Benedictine monks dedicated a monastery to John the Baptist in 1100, the hill came to be known as "Johannisberg" ("berg" being German for "hill").
After changing hands numerous times, it was bequeathed by Hapsburg emperor Francis I to his chancellor, Clemens von Metternich, in 1816. Metternich loomed large at the Congress of Vienna, where Europe was divided after the Napoleonic era; his name is still to be found on Johannisberg's labels, even though the Metternich connection with the estate ended last year with the death of Princess Tatiana von Metternich.
The third president of the USA - and notable bon viveur - Thomas Jefferson, visited the Rheingau in 1788 and wrote that the wine of the "Abbaye of Johnsberg is the best made on the Rhine without comparison … That of the year 1775 is the best."
But names like Eberbach and Johannisberg have not always been synonymous with quality. On the contrary, they were names redolent of the Byzantine incomprehensibility of the German wine classification system and those cloying sweet and semi-sweet wines that lubricated English parties in the 1980s. Yet the days when the Rheingau elicited embarrassed silence in the world of wine are fast receding; the region is re-establishing its reputation for excellent dry white wines.
Where the Rhine finds itself colliding with the Taurus mountains upstream just beyond Mainz, the river turns west, creating a 30km south-facing slope with villages such as Hochheim, Hattenheim and Oestrich. One grape variety has proved itself as the first-born of this slope: once you could find nigh-forgotten grapes here, with names like Orleans and Huenisch. And there are still a few hectares of pinot noir (or spatburgunder as it is called here) and pinot gris. But the undisputed prince of the Rheingau is riesling - even Jefferson referred to the "small and delicate Rhysslin which grows only from Hochheim to Rudesheim".
And the key to the renaissance of riesling in the Rheingau is to be found in my guide on that tempestuous morning in Schlossberg: Heinrich Breuer of the Georg Breuer winery. Georg Breuer has been a pillar of the wine establishment in Rudesheim since 1880, but it was a century later that Heinrich's brother, Bernhard, started a transformation of the Rheingau. Bernhard died young in 2004, but like other pioneers in European wine regions with ossified classification systems - think the Antinori in Tuscany - he had almost single-handedly created a new quality standard.
The revised German classification system of 1971 allowed five quality categories, differentiated on the basis of residual sugar levels. In ascending order of sweetness, these were kabinet, spatlese, auslese, beerenauslese and trockenbeerenauslese. In addition, the elaborate labels with their Gothic lettering contained the names of specific vineyards and winemakers.
Bernhard Breuer was crucial to the founding of the Charta Association in 1984, which later became the erstes gewachs (equivalent to French first growths or grands cru): specific vineyards identified as the best in Germany. These included the Rudesheim vineyards of Berg Rottland, Berg Roseneck and Schlossberg, and Nonnenberg in Rauenthal - in each of which Georg Breuer owns parcels. Since the 1980 vintage from the best of these vineyards - Schlossberg, where Georg Breuer owns 320 of the 20ha - the winery has invited artists to design individual labels every year (a la Mouton-Rothschild). Georg Breuer's Schlossberg remains one of the most sought-after of German wines.
Yet in 2002 Georg Breuer withdrew from the erstes gewachs it had helped found, because the classification started relying too heavily on ripeness as a measure of quality. Henceforth, the Breuer name would constitute its own guarantee of quality. Now they bottle four dry single-vineyard rieslings from their erstes gewachs vineyards - Rottland, Roseneck, Schlossberg and Nonnenberg - as well as generic rieslings from less exalted vineyards. Whenever the climate allows botrytis to flourish, they also make the sweeter ausleses or trockenbeerenausleses.
But when I turn up at the Georg Breuer vinotheque for a tasting after my vineyard visit with Heinrich, it is the dry wines that exude an air of nobility. Dry riesling, Heinrich declared earlier, was after all the original style of this region; the spatlese style was only discovered by accident in 1775 at Johannisberg. And the dry wines of Georg Breuer are a revelation: packed with tropical fruits and floral aromas, yet with a steely dryness and mineral backbone on the palate - complex and round, like a Rubens figure, without ever being fat and shapeless.
As so often in matters vinuous, the delectable contents of the bottle flow directly from a passion for the earth. On that windy morning, Heinrich had recounted how many of the ancient terraces on the slopes above Rudesheim had been destroyed during World War II. After the war, many of the terraces were not rebuilt, leaving the hill to slope smoothly down to the river. "But then erosion became a problem and now we need to let grass grow among the vines to prevent that. Man thinks he knows enough to tinker with nature, but whenever you adjust one thing, two others go wrong," he said.
And then he bemoaned the climate change that has meant that parts of Europe experienced virtually no winter in 2006/07: "We had maybe two cold days."
In the Schlossberg vineyard he explains how Breuer limits its yield to ensure maximum concentration. "The rules allow you to harvest 88 hectolitres per hectare. In our other vineyards, we never harvest more than 45 hectolitres. But here in Schlossberg, we deny ourselves anything more than 15 hectolitres."
Georg Breuer's devotion to the true traditions of the Rheingau go beyond the return to dry riesling. Heinrich showed me a small plot in Rottland where they replanted the ancient variety of Orleans, from which a singular varietal rarity is made. And another plot where they will shortly replant Huenisch.
Of Germany's 100,000ha under vine, only 3000 are in the Rheingau, but the region is something of a cradle of German wine. Here wine and faith mingled in the chalices of Eberbach; here the process of semi-sweet wine was accidentally discovered and German wine became a laughing stock; and here pioneers like Georg Breuer returned to the roots of one of the world's great white wines.