A tale of dynastic skulduggery in early medieval Italy, it includes a stupendous coup de theatre in which the scheming Queen Matilde forces hapless Princess Adelaide to choose between marrying her dim, weedy son Idelberto or else committing suicide. Matilde, providing for every contingency, has brought with her a dagger and a poisoned cup. Choosing the latter, Adelaide prepares to drink, when, to both women's astonishment, Idelberto rushes in, brandishing a sword and threatening to kill himself if she so much as touches a drop.
Not so very long ago, when the London Handel Festival began, a month- long concert series almost entirely devoted to the composer's music, and including a professional production of a minor stage work which flopped at its first performance, would have looked very much like special pleading. Since the 19th century, when extra trains were laid on for Londoners flocking to the Crystal Palace to hear his oratorios performed by mass choirs and monster orchestras, Handel's reputation had taken a nosedive. For most of the musical public, whether in Britain or abroad, his image was little better than that of a facile tunesmith with the good luck to have written Messiah and the Water Music - and the misfortune to have been born in the same year as JS Bach.
Musical orthodoxy decreed that the inevitable compare-and-contrast exercise between the two composers always worked to Handel's disadvantage. Bach emerged as the model scholar, who got everything right because he worked it out neatly in advance. Handel was the naughty boy, slapdash, half-hearted, cutting corners and cheating off others. It never seems to have struck those making this ultimately pointless comparison that the two men were distinct creative personalities, writing for vastly differing audiences. To a lot of people who ought to know better, one German Baroque composer in a big white wig looks very like another.
By the 1985 tercentenary commemoration of his birth, Handel had become a classic victim of what might be called the Iceberg syndrome, in which only a faction of an artist's best work is visible above the waterline of neglect. The great dramatic oratorios, works like Athalia, Solomon and Belshazzar, hung on here and there, though their occasional performances at the Proms or the Queen Elizabeth Hall were risk ventures, "box office poison" in concert-promoter speak. How, in any case, was it possible to make them work under the impacted dust of Victorian evangelical piety, and memories of pneumatic contraltos in flowered hats gargling into the rafters of some provincial Corn Exchange?
An even worse fate had overtaken Handel's operas. Conventional wisdom (aka cultural indolence and incuriosity) long ago decided that these were resistant to any serious presentation on a contemporary stage. The standard Baroque aria form, with its reprise of the opening material after a middle section in a different key, was felt to be a strain both on dramatic credibility and on an audience's ability to stay awake. Long passages of harpsichord- accompanied recitative might be tolerable in Mozart, but as employed by Handel they were simply an effective reminder of the ways in which opera, with the aid of a little Wagnerian Vorsprung durch Technik, had streamlined itself since his day.
The plots, with their female warriors, magic islands and long-lost brothers identified by strawberry marks, were fatuous, happening in a classical never-never land inhabited by people whose names, Bradamante, Cleofide, Polinesso, sounded like Formula One racing cars or different types of pasta sauce. There were no choruses worth speaking of and hardly any ensembles, while the orchestra was just a mimsy little combo of fiddles and oboes. Finally, since the male principals, at the operas' earliest performances, had mostly been Italian eunuchs, how could we possibly do these works justice? As one Handel scholar so neatly put it, "nowadays there is no humane answer to the castrato problem."
Now and then, an enterprising revival showed how bogus or else purely nonsensical such ideas of Handel opera actually were. A Decca recording of Alcina, made in 1962 as a vehicle for Joan Sutherland, quickly became a classic for its thrilling vocal realisation, of the opera's eroticism and emotional ambivalence. Every autumn at Sadler's Wells the Handel Opera Society used to feature selected stage works, whose am-dram milk-bottle- tops-and-string production values were offset by a line-up of superb soloists. Down at the Unicorn Theatre in Abingdon, meanwhile, the husband-and-wife team Alan and Frances Kitching made Handelian operatic miracles happen on an even tinier stage and the proverbial shoestring budget, with the help of an undergraduate band in the pit and monsters played by local schoolkids. If it wasn't exactly the King's Theatre Haymarket, where many of the operas received their premieres with stellar casts and an orchestra of international virtuosi, we were grateful, all the same, for a chance to hear the music.
How did this all change "in a moment, in the twinkling of an eye", as the bass soloist famously thunders in Messiah? Which particular spot in the late-20th century Zeitgeist did Handel succeed in hitting during those 1985 tercentennial junketings, to get himself out of the reference books and back on the stage where he belongs? The revival of authentic performance practice in Baroque music undoubtedly helped, revealing that with the more grainy, physical sound of a small ensemble of period instruments, alert to heady rhythms and keen phrasing, Handel's notes can make your hair stand on end. As if to prove the point, labels like Harmonia Mundi, L'Oiseau Lyre and Hyperion began pampering us with works such as Joshua, Giustino and the incidental music to Smollert's lost play Alceste, not exactly Desert Island essentials but welcome nonetheless.
Handel, meanwhile, has become a class act in the world's major opera houses, so much so indeed that certain pieces like Giulio Cesare in Egitto and Ariodante are fast achieving standard status in the international repertoire. Opera North is limbering up for Radamisto, 1720s London's hit show, ENO has a new production of Semele and there's talk of an Agrippina with Lesley Garrett. It's at Glyndebourne, however, where the spectacular breakthrough has been made in winning new audiences for Handel. Theodora, not written for the theatre and with more meditation than confrontation, was the surprise winner of the 1996 season, and last year's 1930s Hollywood- style Rodelinda had its impact sharpened by the star countertenor Andreas Scholl and the designer glamour of Anna Caterina Antonacci in the title role. Audiences in Edinburgh and London, revelling in the wayward inspirations of choreographer Mark Morris's L'Allegro, il Penseroso ed il Moderato, found themselves captivated as much by the unfamiliar score's kaleidoscopic tone-painting as by the beauty of the dance itself.
Oh, and let's not forget My Night With Handel, a cheekily brilliant C4 film by Alex Marengo and Debra Hauer, setting a collage of hit numbers against backdrops of Soho nightlife and a Richard Rogers-Norman Foster Londonscape in which the music seemed perfectly at home. Suddenly Handel is everywhere, with or without the white wig. Even TV commercials feature snatches of Zadok the Priest and the Opus 3 concerti Grossi. So what explains our ardent embrace of the composer we formerly either spurned or ignored?
Singers have always loved Handel because of his gift, noted by contemporaries, for coaxing and flattering even the most mediocre voice so as to burnish it with genuine star quality. Audiences entering the opera home with preconceived ideas as to the dullness of da capo arias cave in, overwhelmed by the unforgettable potency of his melodic lines. Cutting-edge directors like David Alden and Peter Sellars speak with such fervour about Handel as a theatre animal that the ink seems scarcely dry on his scores. As for the oratorios, the punters are flocking back, without their prayerbooks and dog-collars, and more passionate than those Victorians at Crystal Palace, a veritable soccer crowd indeed, if a recent Proms performance of Deborah is anything to go by.
It was Mozart, his admirer and conscious imitator, who spoke of Handel's unique gift for achieving great effects through simple means, and it's Mozart whom he foreshadows in the range of his moods and sheer formal versatility. Some writers on music like to call him "Shakespearean", because of the massive array of human emotions and character types his imagination unfolds.
A cynic might say that Handel is popular again because his works, with their tiny forces, are so attractively cheap to perform in these cost- cutting times. Audience reaction, surprised and enchanted, suggests there's rather more to it than this. Together with the sophistication and elegance we expect from a man who was a connoisseur of fine paintings and good wine, there's a wisdom and humanity whose grounding in direct personal experience enfolds us all.
A friend of mine, mad for the late Romantic big symphony sound, summed up the effect after sitting through a performance of Belshazzar. "You're standing on the edge of a cliff, ready to end it all. Mahler says "Go on, jump!" - Handel says "Let's do dinner instead."