Wagner, born in Leipzig on May 22, 1813, played by his own rules. Widely influential, he dared take opera beyond the realm of neat blood-and-gutsy rituals-way beyond. In his aptly named music-dramas, he expanded contemporary concepts of what human singers and players could achieve.

He began his supremely eccentric, also egocentric, career as a conductor, an avid champion of Beethoven (especially the Ninth Symphony), Mozart, Weber and Gluck. Upon encountering the overwhelming expressive intensity of the diva Wilhelmine Schröder-Devrient in Bellini, he became obsessed with the challenge of fusing music and literature in an essentially new guise. Significantly, he based his relatively modest second opera, Das Liebesverbot (1836), on Shakespeare's Measure for Measure.

Within a decade he was immersed in the misty Teutonic myths that led to the massive Der Ring des Nibelungen. This epochal cycle, which lasts more than 15 hours and sprawls over four evenings, made huge demands on the artists on stage and in the pit, not to mention the patrons out front.

Wagner required tireless voices that could cut through a massive orchestra, an orchestra that often served as a primary force in the narrative (mere accompaniment would be anathema). Before Wagner, there had been no such thing as a Heldentenor or Hochdramatisch soprano, specialized voices required to meet Wagner's musical demands. While some would-be heroic singers succumbed to the inherent Wagnerian rigors, a new, select breed eventually emerged to meet the composer's hardly reasonable demands. It was Wagner who ultimately created such 20th-century paragons as Lauritz Melchior, Kirsten Flagstad and Birgit Nilsson.

Wagner perfected the concept of the Leitmotif, an evolving musical theme associated with a specific character, object or emotion. This device could allow the orchestra to reveal secrets unmentioned in the text. That text, not incidentally, was invariably written by the composer himself. He had no interest in collaborating with anyone from another creative sphere, no need for an outsider librettist.

In his maturity, Wagner unified music and drama in long, essentially unbroken strokes, seldom pausing for anything like a set piece or aria. With the score through-composed (Durchkomponiert), Wagner's action progressed without interruption, without flagging tensions. Wagner's writing heralded music of the future (Zukunftsmusik), employing a highly chromatic language that stretched tonality and harmonic definition beyond contemporary norms.

On a personal level, Wagner was not exactly what one might call a nice man. Unabashedly egomaniacal, he used and abused, embraced and discarded people who could help him, and did so at whim. He took useful advantage (understatement) of King Ludwig of Bavaria. He tended to ignore any prim notion of social convention, enjoying affairs with a succession of women who happened to attract or flatter or inspire him (preferably all three). It may be worth remembering that the ultimate union with his devoted wife, Cosima, began while she was married to his devoted acolyte, the conductor Hans von Bülow.

Reluctant to have his works produced-distorted?-by ordinary opera companies, he created his own revolutionary theater and his own hopefully sacrosanct festival in the sleepy Franconian town of Bayreuth. Despite controversial modernist stagings, it remains a mecca for an eager international public even today.

When not making music, Wagner was a politician of sorts, a zealot unafraid of espousing controversial causes. In 1849 he sided with the revolutionary uprising in Dresden, then fled to Weimar and Zurich to avoid arrest. He was openly anti-Semitic, and many have interpreted some of his unpleasant characters-Mime and Alberich in the Ring, Beckmesser in Die Meistersinger von Nurnberg-as Jewish caricatures. Long after his death in 1883, he became an easy symbol of German nationalism, idealized by Hitler in particular and by the Nazis in general.

Verdi, born in the village of Le Roncole, near Busseto, on October 10, 1813, may not have been a fiery revolutionary, personally or publicly, like Wagner. Still, he was significantly influential, poignantly emotional and, with the passage of time, capable of progressive invention. He, too, was essentially a man of the theater, yet compared to Wagner, he was moral and kindly, straightforward and gentle.

Despite the obvious dissimilarities, Verdi did share some traits with his German compatriot. He also admired Shakespeare and, in addition to his successful middle-period Macbeth, he found fulfillment in his final masterpieces, Otello and Falstaff (the latter adapted from The Merry Wives of Windsor plus portions of Henry IV). Significantly, however, Verdi relied heavily on the collaboration of a poetic librettist, in this case the sometime composer Arrigo Boito. Creating both words and music was not for Verdi. Although both Otello and, to a distant degree, Falstaff make primitive use of Leitmotifs, Verdi disparaged the Wagnerian practice.

At various times, Verdi considered writing an opera based on King Lear, but, daunted by the great challenge, he never followed through. A Lear who sings did not become a reality until Aribert Reimann and Aulis Sallinen wrote their expressly un-Verdian operas in 1978 and 2000, respectively. Neither effort, it must be noted, achieved anything like success on a Verdian scale.

After Verdi's first wife and two children died between 1838 and 1840, the composer vowed to write no more music. The vow was fatefully broken, however, when he was persuaded to write Nabucco in 1841. "This is the opera with which my artistic career really begins," the composer recalled. "And though I had many difficulties to fight against, it is certain that Nabucco was born under a lucky star." In 1859 Verdi married the soprano Giuseppina Strepponi, with whom he had lived for a decade.

Verdi always protested, perhaps too much, that he lacked technical sophistication. "Of all composers, past and present, I am the least learned," he wrote. "I mean that in all seriousness, and by 'learning,' I do not mean knowledge of music." Wagner, who could not include modesty among his strongest virtues, never wrote anything like that. Nor did he ever write anything as melodic or as popular as Aida, with its unique fusion of the grand and the intimate, the heroic and the subtle, the portentous and poignant. [James Conlon will conduct Aida with the Chicago Symphony Orchestra on August 3.]

While Wagner created the Bayreuth Festspielhaus as his vast personal shrine, Verdi was content to establish the Casa di Riposo per Musicisti, a simple rest home for aging musicians in Milan. "Of all my works," the composer reflected, "the one that pleases me most is the Casa, which I had built in Milan to shelter elderly singers who have not been favored by fortune, or who when they were young did not have the virtue of saving their money. Poor and dear companions of my life!" Verdi, who died in 1901, is buried there together with his wife.

Politically, Verdi's well-documented sympathies favored Italian separation from Austria. In 1860, following the war of independence, he was elected deputy in the first Italian parliament, a post he held for five years. His profoundly moving chorus "Va pensiero," written for the Hebrew slaves in Nabucco, has become a popular, even symbolic emblem of Italian patriotism, freedom and unity. Three years ago an Italian senator, Umberto Bossi, actually proposed (in vain) that the hymn become Italy's national anthem. Earlier, the same music sometimes had been appropriated in support of Fascism, as Verdi was idealized by Mussolini.

Benjamin Britten is not a household name, not an international hero like Wagner and Verdi. Not yet, anyhow. He was born a century later, in Lowestoft, Suffolk, on November 22, 1913. Relatively modest, mild-mannered and sensitive, he wrote scores, big and small, that were reflective, demanding, harmonically conservative yet subtly inventive. He was a master of eloquent drama and, equally rare, elegant wit. According to a reliable website, more Britten operas are played throughout the world than those of any other composer born in the 20th century.

Ian Bostridge, a fine tenor who has specialized in Britten's music-much of it created for the composer's life partner, Peter Pears-put it this way in a splendid essay for London's Times Literary Supplement: "As a public face of classical music in Welfare State Britain, Britten fulfilled a role as iconic as Handel's had been."

For most impractical purposes, Britten's primary breakthrough occurred in 1945 with the premiere of his great opera, Peter Grimes. A bold study of alienation and loneliness, outsider themes painfully close to Britten's heart, Grimes brought the composer widespread fame and reasonable fortune.

Britten and Pears, both confirmed pacifists, spent three years in the United States, starting in 1939. When they returned to England amid the war effort, they registered, controversially but without negative incident, as conscientious objectors.

They eventually settled in Aldeburgh, Suffolk. The remote seaside town became their living/working/performing center, until Britten's death in 1976 and Pears's a decade later. It was here that Britten wrote his Shakespeare opera, A Midsummer Night's Dream (1960). It was here that his music took on a new degree of austerity. And it was here in 1966 that the thinking person's composer, an agnostic, wrote an intimate "parable for church performance," The Burning Fiery Furnace. Its crucial theme: a confrontation between idolatry and monotheism.

Although the surface subject may be exotic, the treatment is eminently introspective yet assertive, troubled yet serene, creative yet orderly. The music apparently reflected the man.

Pulitzer Prize-winning critic Martin Bernheimer covers music in New York for the Financial Times.