NIGHTS AT THE OPERA.

Lorenzo Da Ponte, who wrote the librettos for "The Marriage of Figaro," "Don Giovanni," and "Cosi Fan Tutte," has been a troubling item for Mozart scholars. Almost everyone agrees that Da Ponte supplied Mozart with better texts than the composer had ever worked with, and that the operas the two men produced together are among the greatest in the international repertory. But Da Ponte's contribution has often been put down to mere cleverness, stage smarts--not art, not soul, not like Mozart. This trend may be changing. In 1985, an exemplary biography appeared, "Lorenzo Da Ponte: The Life and Times of Mozart's Librettist," by Sheila Hodges. In 2000, an English translation of Da Ponte's own "Memoirs," long out of print, was republished by New York Review Books. This year, there have been two further biographies: "The Man Who Wrote Mozart: The Extraordinary Life of Lorenzo Da Ponte" (Weidenfeld & Nicolson; [pounds sterling]18.99), by Anthony Holden, the music critic of the London Observer; and "The Librettist of Venice: The Remarkable Life of Lorenzo Da Ponte--Mozart's Poet, Casanova's Friend, and Italian Opera's Impresario in America" (Bloomsbury; $29.95), by Rodney Bolt. David Cairns, in his new book, "Mozart and His Operas," praises Da Ponte lavishly and deplores other musicologists' condescension toward him. Such tributes may just be scraps thrown from the feasting table laid this past year for Mozart's two-hundred-and-fiftieth birthday. Nevertheless, Da Ponte is now getting some attention.

He was born in 1749, in Ceneda, a small town north of Venice. His name was Emanuele Conegliano. He was the first son of a tanner; his mother died when he was five. They were Jews. When Emanuele was fourteen, his father decided that the family would convert, to better their position. The Bishop of Ceneda, Lorenzo Da Ponte, received them into the Church. It was customary for converts to take the surname, and for eldest sons to take the full name, of the presiding priest, so Emanuele became Lorenzo Da Ponte.

Prior to his conversion, he had had almost no education. But Bishop Da Ponte looked after his new Christians. At his expense, Lorenzo, with his two brothers, was sent to the local seminary, and there he caught up fast. After two years, he relates in his "Memoirs," he could write a long oration in Latin, together with fifty-odd lines of Latin verse, in half a day. He also acquired Hebrew and Greek. But his great passion was for Italian literature. In less than six months, he says, he memorized much of Dante, Petrarch, Ariosto, and Tasso. Poetry became his obsession. In class, when he and his best friend got bored, they would compose verse, one writing one line, the other writing the next. In his own poems--of which, he says, he wrote and burned two thousand during his early years in the seminary--he emulated his classical models, "trying my hand repeatedly at every style of meter and composition, striving to imitate the most beautiful thoughts." These years of playing with poetry--translation, adaptation, collaboration, speed, joy--were his training for the notably impure, improvisatory job of eighteenth-century libretto writing.

When Lorenzo was nineteen, Bishop Da Ponte died and his subsidy of Lorenzo's tuition ended. Lorenzo was told that he could transfer to the seminary at nearby Portogruaro, but that, if he did, he would have to become a priest, a calling, he writes, "wholly contrary to my temperament, my character, my principles, and my studies." He submitted. At the new seminary, he rose quickly to the position of instructor, then professor, then vice-rector. In 1773, at the age of twenty-four, he was ordained, and six months later he escaped to Venice.

The Venetian Republic was in rapid decline at the time--twenty-four years later, it surrendered to Napoleon without a fight--but, meanwhile, the Venetians were having a party. Those who could afford to went every night to one of the city's seven opera houses. When the show was over--usually, around 2 A.M.--they repaired to the gambling houses. Carnival occupied nearly half the year. Hodges writes, "Masks were universally worn, and this gave the wearers a license that would otherwise have been impossible. It also led to a particularly classless society. . . . Nobleman and beggar, artisan and poet, gondolier and visiting royalty mingled under the clear winter sky."

This, then, was a good place for a young man who, after ten years in a cassock, was looking for some excitement, and in Venice, Da Ponte says, he devoted himself exclusively to "cards and love." The first love was Angiola Tiepolo, an impoverished noblewoman--tiny, pretty, and violent-tempered--whose husband had just left her, apparently for good reason. Da Ponte moved in with Angiola and her equally dissolute brother. Both were gambling addicts, and Da Ponte soon became one, too.

At this point, Da Ponte's book becomes a lot of fun. Events tumble out of it like kittens out of a bag, and some are quite fantastic. One evening, Da Ponte encounters a beautiful, mysterious young lady. ...