When I realized Rene Jacobs was my favorite classical musician, I was driving my car. As I drove, I was listening to a Harmonia Mundi CD on which Jacobs conducts "The Coronation of Poppea," a Monteverdi opera written way back in 1643, and in its unsparing view of life more modern than most operas written now.
Early on, a hapless lover lurks outside the palace of a woman who's flagrantly sleeping with somebody else. As the lover whines, he's interrupted by the bodyguards of the man inside, who've awakened and wonder who's carrying on. They sound so tired, bored and mocking that it's hard to believe they're opera singers; they sound like they're interrupting the recording itself.
And Mr. Jacobs's CDs are almost always this lively, and, at times, outrageous. He started his career as a singer, a countertenor. Then he became a conductor, leading performances of Baroque music, played on the musical instruments of its era, which are very different from ours -- a natural evolution, since he'd sung Baroque music and conducts with an arresting spark. Some of his early CDs of Handel operas ("Flavio" and "Giulio Cesare") are merely terrific, but "Poppea" is in another class -- more real than life.

One reason for that is Mr. Jacobs's freedom with the music. Opera, in the 1640s, wasn't fully written down. Composers would sketch out what they wanted, showing what the singers ought to sing, along with just the merest outline of the instrumental parts. The writing could be sketchy, Mr. Jacobs knows, because musicians then would fill it out by improvising, and that's what he lets his own musicians do, though he'll also write out ideas for them, filling out the sketchy scores with often wild imagination. He's not the first to do this, but he's by far the freest, and the freedom he encourages seems to wake the singers up.
And in his 1999 recording of Mozart's "Cosi fan tutte" he gets even crazier. One imponderable in Mozart's Italian operas is the role of a keyboard instrument, typically a harpsichord or fortepiano (a forerunner of the pianos we have now). Parts of the piece are accompanied only by an improvising keyboard, joined by a single cello, but we know that the keyboard player would also improvise everywhere else in the piece -- and that when the opera was premiered, the keyboard player was none other than Mozart himself.
What, exactly, did Mozart play when he took this improvising role? On an informative and delightful CD-ROM that comes with the recording, Mr. Jacobs shares some authoritative 18th-century advice. This comes from Mozart's father, Leopold, a notable musician in his own right, who advised keyboard players to be discreet, and only play "simple and incisive" chords. But Mr. Jacobs -- with the panache I love him for -- can't accept that.
"One can hardly believe," he writes in the CD liner notes, "that Mozart -- imaginative, irrepressible, and a genius at improvising -- would have limited himself that way." So Mr. Jacobs sets his keyboard player free, and as a conductor shapes the music so flexibly that he wonders whether Mozart would approve. He imagines himself (again on the CD-ROM) somehow asking Mozart's opinion -- and then phoning Harmonia Mundi to tell them that Mozart would not want the recording to appear.

But then that's why this performance is so unfailingly alive -- because Mr. Jacobs (just like Mozart himself) won't follow any rules. Harmonia Mundi, I might add, releases every CD I've mentioned here, and is the most artistic classical label around; they also record violinist Andrew Manze, who does for Baroque violin music what Mr. Jacobs does for Baroque opera. And this month they've rereleased five Jacobs operas in limited editions, at lower prices, including some of what I've mentioned here.
Also just released -- last month, at full price, but spectacularly worth it -- is the wildest Jacobs opera yet, his Harmonia Mundi recording of Handel's "Rinaldo." This piece, full of flying chariots and fire-breathing dragons, was exhilarating entertainment back when it was first staged in 1711, complete with all the spiffiest 18th-century special effects. Mr. Jacobs, bless him, understands that the music, too, went over the top, and he uses the printed score only as a starting point, adding percussion, glorious improvisations, and, in one place, singers joining their mocking voices with what's written only as an instrumental line.
At the end of one extravagant aria, the timpanist, Charlie Fischer, just about drowns out the rest of the orchestra, slamming away ad lib on his drums, catching just the right tone of pomp and menace. In 1711, "Rinaldo" wasn't anything we'd recognize as classical music; the term, in fact, didn't exist, and musicians didn't perform with anything even close to the formality we take for granted today. Mr. Jacobs, more than anyone else I've heard, blows away the prim domesticity of our classical music world, and shows us past centuries as they really might have been.