James Levine will conduct a concert at Carnegie Hall tonight, which is no big deal – Mr. Levine conducts at Carnegie Hall frequently, usually with his Metropolitan Opera orchestra. But what is a big deal is that he will be conducting the Boston Symphony Orchestra, and as its music director. He became that last Friday, for all intents and purposes, when he conducted his first concert as BSO music director, in Boston’s Sym phony Hall. The program was the same as tonight’s at Carnegie – one work, Mahler’s Symphony No. 8, nicknamed the “Symphony of a Thousand.” Mr. Levine has long been a Mahler specialist. Or we would call him a specialist, if he didn’t specialize in pretty much all of music.

He is one of the most versatile musicians of our time, an opera conductor, of course, and a symphonic conductor, and a pianist, playing in all sorts of situations. The breadth of his activities is astonishing. He does everything but compose, so far as we know. (He may have something in the drawer.) One probably has to compose in order to be counted a complete musician, but Mr. Levine is as complete as a non-composer can be.

In addition to his conducting and playing, Mr. Levine is a wonderful talker about music. Not every great musician is; some can only grunt, or shrug their shoulders. But Mr. Levine can talk your ear off, illuminatingly. Marilyn Horne calls his master classes “religious experiences.” And if you would like to “hear” Mr. Levine, you can pick up a book by Robert C. Marsh called “Dialogues and Discoveries: James Levine: His Life and His Music.” (That “His Music” is groan-inducing – one’s music ought to be music that one writes – but one can well imagine the publisher insisting on the title.)

For many years, many of us have wished a major symphonic podium for Mr. Levine. He is a conductor who has chosen to spend the bulk of his career in opera. He has been with the Met for more than 30 years now. The Met, and opera, have been very lucky to have him: Seldom does a conductor of that rank devote himself so wholeheartedly to opera. In Europe, the pattern was always that one started in an opera house, “graduated” to a symphonic podium, and occasionally revisited the opera house, just to keep a hand in, and conduct some of the better repertoire. Mr. Levine has made opera his principal activity.

When I say “major podium,” I should apologize to Munichers, for Mr. Levine led the Munich Philharmonic for five seasons, from 1999 to this year. For that matter, he has stood before major orchestras all his life, notably the Berlin Philharmonic, the Vienna Philharmonic, and the Chicago Symphony Orchestra. In fact, he was music director of the Ravinia Festival – the CSO’s summer enterprise – for 20 years (1973 to 1993).

But Mr. Levine’s directorship of the BSO? That should be different. Here he has a chance to put his stamp on one of America’s “Big Five” orchestras, and not just in the hot months. That means a lot. We can hope it means, among other things, a series of enduring recordings.

He was a wunderkind, born in Cincinnati, a pianist who made his concerto debut at 10. He would later study the instrument with Rosina Lhevinne, and – critically – apprentice as a conductor under George Szell at the Cleveland Orchestra. He shares many of that old master’s traits, including discipline, respect for the composer, and what might be called musical integrity. Mr. Levine’s education could hardly have been better, and he seems to have absorbed it all.

So good did his Met orchestra become that he began to lead it as a stand-alone orchestra – a symphonic orchestra – taking it on the road, making some recordings. Is the Boston Symphony really a better orchestra? Well, fortunately, one does not have to choose.

As BSO publicists tell us, he is the 14th conductor in the orchestra’s 123-year history, and the first who is American-born. (In music, people make a lot of nationality – and these are typically people who disdain nationality in about every other area.) He succeeds Seiji Ozawa, who headed the orchestra for 29 years. Many observers think the orchestra declined badly in this period, particularly the last half of it. Then again, I knew a musician who, instead of saying Erich Leinsdorf’s name, would simply refer to him as “the man who ruined the Boston Symphony.” (Leinsdorf was music director from 1962 to 1969.)

If Mr. Levine succeeds in making the BSO a Levine orchestra, the Bostonians should be a model of technical discipline and musical inspiration (in addition to plain old musical common sense, which is not so common, sadly).

But can he handle it? Can Mr. Levine handle the load of the BSO, and his continuing (though reduced) work at the Met, and his chamber-music participation, and his summer-festival-ing, and all the other things he does? There has been talk about his health, and whether it is hampering him. He now conducts sitting down; on some occasions he seems defeated, sort of limp. There is some worry that, now that he has this major symphonic podium, it is “too late” – he will not be at his best; the old Jimmy is absent, or appears only sporadically.

To use a boring phrase, we will see. But what we don’t have to wait to see is that James Levine is one of the great conductors of his time, and, more than that, of history. He also has an extraordinary love of music, one of his most conspicuous traits.

But don’t all professional conductors, and professional musicians, have a love of music? Not on your life. And those who do love, do it in varying degrees. Mr. Levine has never lost what might be called a child’s love of music (to go with supreme adult wisdom). Look at his face, for example – his upturned, singing face – when he conducts the final, beyond-joyous chorus in Beethoven’s “Fidelio.” This is what music should do, and be.

As for Mahler’s Symphony No. 8 – fingers crossed.