James Levine was in his chair last night, doing one of the things he does best: conduct a Mozart opera. The Met began a run of “The Marriage of Figaro,” with a very good cast. But the most important “cast member,” in this opera as in others, is the conductor. It is on him that the overall feeling of the piece depends. You would rather have a good conductor and so-so singers, than a so-so conductor and good singers. (I generalize.)

The opera begins with – what else? – the overture, and we might ask how many times Mr. Levine has conducted this gem, both in the opera house and in the concert hall. A thousand? Five hundred? Do I hear 250? A lot, anyway. Last night’s was not his best performance, as the orchestra was not quite together, and things were a little workaday – also a little muted. Still, the overture does not lose its thrill, and the audience applauded happily.

I pause to insert an anecdote: Years ago, I took a friend of mine to a performance of “The Marriage of Figaro.” He had never been to a classical-music performance of any kind. After the overture (very poorly played), he leaned over to me and said, “That’s the greatest thing I’ve ever heard.” I sort of pitied him: If he attended concerts and operas steadily for 100 years, he would never hear better.

In the first act, Mr. Levine was a little hard-driving at times, but his discipline is to be appreciated. He showed his knack for just tempos. And he has the gift of making a Mozart opera – certainly its individual acts – a unified piece of music, not a series of episodes. You might describe his approach as symphonic. He will not let singers get in the way of the score.

In the title role was the Canadian bass-baritone John Relyea. We have run out of ways to praise him, so I will merely repeat: He has one of the most enviable voices in the business, a voice rich – even plush – but also streamlined, which is extraordinary. If you have a voice like that, the world will be your oyster. His arias were both graceful and substantial. He is full-toned, yet Pinza-clean. His diction is excellent, although – if I may pick a nit – I wish the “r” in his “signore” would not sound double.

The voice is commendably Mozartean, but it has more power than you might think: Mr. Relyea summons it at opportune moments. And when he did “Non piu andrai,” he was the complete master of that stage.

Portraying Susanna was the Hungarian soprano Andrea Rost, whom we have heard at the Met as, for example, Gilda (in “Rigoletto”). She negotiated that role extremely well; she handled Susanna smartly, too. The voice is not always beautiful – it has some metal in it – but it is never unattractive. Last night, Ms. Rost displayed what you might call a musical modesty, and this was a modesty becoming to the part. She is especially good at the quick half-spoken, half-sung line: a necessity for Mozart.

Jossie Perez, the Puerto Rican mezzo, was Cherubino, and she did not have her best night. She was passable, in “Non so piu,” “Voi che sapete,” and elsewhere: but she will do better. A quite able Countess was Janice Watson, the British soprano. She brought good breath control, and the elegance and dignity necessary to the part. Our Count was Polish baritone Mariusz Kwiecien. He was lusty, menacing, petulant – exactly what he needed to be. And he sang with assurance.

Paul Plishka was a savvy Don Bartolo, and Jane Bunnell was a characterful Marcellina. And Michel Senechal’s Don Basilio? A piece of work. Mr. Senechal does not go over the top in this part, but he has fun bumping up against the top, you might say.

Almost every singer remarks that Mozart is the hardest composer to sing. And recall what Arthur Rubinstein said about piano playing: “Mozart is too easy for children, too hard for adults.” On the whole, last night’s participants made Mozart singing appear fairly easy.

The production is Jonathan Miller’s from 1998, with those inviting and apt sets designed by Peter Davison. This, I dare say, is how “Figaro” ought to look.

Outstanding in the orchestra were Kevin Murphy, harpsichord, and David Heiss, cello, who were the stalwart, accurate, and musical continuo players.

“Le Nozze di Figaro” will be performed again February 7 at 8 p.m., February 12 at 1:30 p.m., and February 18 at 8 p.m. (Lincoln Center, 212-362-6000).