The Emerson String Quartet launched an ambitious series on Thursday night – a series they have undertaken many times before. They’re playing the complete Shostakovich string quartets, at Alice Tully Hall; during the same period, the Alexander String Quartet is doing the same thing, at Baruch College. The ESQ finishes up on May 14; the ASQ concludes tonight. The Shostakovich string quartets are so great, they can bear two such series, or more.

Shostakovich wrote 15 of them – 15 string quartets – meaning that an ensemble can perform them all in five neat concerts of three works each. Coincidentally, Shostakovich also wrote 15 symphonies. At Avery Fisher Hall, the Russian conductor Valery Gergiev is performing them all, with two different orchestras (the Kirov Orchestra and the Rotterdam Philharmonic).This seven-concert series will conclude next fall.

Why this explosion of Shostakovich? This year marks the centennial of his birth. I have frequently remarked on two phenomena in music: anniversaryitis (as I call it) and completeness mania. When the two of them join up, look out.

Although both the complete quartets and the complete symphonies make for fascinating and rewarding listening. Shostakovich wrote symphonies throughout his life, the first when he was a teenager, in 1924-5, and the last in 1971, four years before he died at the age of 68. He did not write his first string quartet until 1938, when he was already a mature composer. (Well, there’s nothing immature about the Symphony No. 1.) The last string quartet, No. 15, came a year before his death. In the symphonies and the string quartets, you can hear the arc of Shostakovich’s life, and much of the life of the Soviet Union.

The Emerson String Quartet, like the Alexander String Quartet, is playing the quartets in chronological order, which makes sense. Mr. Gergiev is not conducting the symphonies in chronological order – which also makes sense. The symphonies need some splicing around, to make balanced, interesting concerts. With the quartets, you can just march right along.

Each quartet has a story behind it, written in a particular time of Shostakovich’s harrowing life, under particular circumstances (usually unwelcome). For example, the first quartet was written in the aftershocks of the Great Terror.The second was written during the war. The third was written a year after the war ended – and so on. It’s interesting to consider each quartet in historical and biographical context. But, ultimately, the quartets are simply music, to be heard and judged that way.

The ESQ has lived with the Shostakovich string quartets for a very long time, and they have decided ideas about them. In the late 1990s, they made a celebrated recording of them (for Deutsche Grammophon). And the group was in pretty good shape on Thursday night, for the first three string quartets.

The String Quartet No. 1 in C major, Op. 49, is a sunny, pleasant affair (as its key might suggest). Shostakovich called it “somewhat naive.” And yet there is some disquiet beneath the surface, as you might expect, from this composer. In the first movement, the violins had trouble with intonation, and they played with a feebleness they perhaps didn’t intend.The sound of the cellist, David Finckel, was extraordinary: extraordinarily good. He plays with a beauty and richness that can astonish you. But he can also rattle your bones, with rawness or grit.

The sound of the violist, Lawrence Dutton, is extraordinary too (and versatile). In the second movement of the First Quartet, he sang duskily and movingly.

Sounds aside, the ESQ played together throughout this quartet, as they would the other two. If chamber playing lacks ensembleship, it lacks a lot – no matter what other virtues are present.

The String Quartet No. 2 in A major, Op. 68, is a stupendous work of music, in which Shostakovich displays much of his imagination and smarts. The ESQ displayed some imagination and smarts, too. Gone was the feebleness in the violins. And, in the first movement, Mr. Finckel played with a striking urgency, suitable to the music.

The second movement – Recitative and Romance: Adagio – can seem like a violin concerto, with some Hebrew wailing around. (Shostakovich liked to do this, in a variety of music.) Eugene Drucker handled the part nicely. Yet there are some questions to ask, and these are the questions one frequently asks when Shostakovich is performed.

Is it too beautiful? Alternatively, is it too ugly? Then: Is the playing too serene, too relaxed? Alternatively, it is too chaotic, too mad? If the ESQ had a fault on Thursday night, it was an erring on the side of beauty or relaxedness, sometimes crossing into blandness. (This despite the urgency of Mr. Finckel I mentioned, and other such moments.)

A quick word about the third movement of the Quartet No. 2: It is a waltz, but a waltz with a twist – not so much Strauss family as Addams family. Shostakovich himself referred to it as a “valse macabre.” It is one of those shiver-making pieces from this composer, and the ESQ handled it adequately.

Of interest about the Quartet No. 3 in F major, Op. 73, is the third movement: Allegro non troppo, a brief, brutal thing (which Shostakovich associated with “the forces of war unleashed”).The ESQ uses this as an encore, and, indeed, you will find it on their album of encores (a superb disc, also on Deutsche Grammophon). On Thursday night, they attacked it well, although not as hungrily or crisply as they have in the past.

In any case, when the evening was over, the public applauded lustily, for this honored chamber ensemble, and also for Shostakovich.

***

Those in charge of the New York Philharmonic apparently believe in playing to one’s strengths – they have Sir Colin Davis leading the orchestra in Mozart, Berlioz, and Sibelius. The nearly octogenarian Sir Colin is one of the best conductors we have, experienced and adept in any music. But he is particularly associated with the three composers I have named.

Last week, he conducted a program of Mozart and Berlioz. This week, he will conduct a program of Mozart and Sibelius. Last week’s program – of which I heard the Friday performance – consisted of two works: Berlioz’s loved song-cycle “Les Nuits d’ete” and Mozart’s loved (and long) Serenade in D major, K. 250, called “the Haffner.”

The song-cycle, of course, requires a singer, and he was Ian Bostridge, the British tenor. “Les Nuits d’ete” starts out with one of the most felicitous of all songs, “Villanelle.” It brims with tingling anticipation. But Mr. Bostridge didn’t quite sing it that way: He was casual, pretty, and dull (I’m afraid).

The ensuing songs suited him a little better, or he suited them a little better – few do brooding Romanticism as well as Mr. Bostridge. The tempos he and Sir Colin chose – or one of them chose – were deliberate, but pulled off. In some songs, Mr. Bostridge floated some really beautiful high notes.

But trouble returned with the final song, the ecstatic, rhapsodic “Ile inconnue.” Mr. Bostridge sang it like a British intellectual – like the British intellectual he is. Now, a British intellectual is indubitably a fine thing to be – but not necessarily in “L’Ile inconnue.”

Sir Colin led the orchestra with his typical elegance and taste. The textures he achieves are wonders to behold.

And I might report something funny: Between the songs, the audience coughed – a lot – as audiences tend to do. During one pause, Mr. Bostridge coughed loudly too, in mockery of them, and perhaps to chasten them.

Mozart wrote his Serenade, K. 250, in the American year of 1776, and he did so for a wedding in the family of some friends (the Haffners). I happen to think a little less of this work than the world at large does, but there is unquestioned genius in it – it’s Mozart after all. And if the Serenade is background music – which, in a way, it is – it is background music of the very highest order.

As he conducted, Sir Colin showed all his skills as a Mozartean. He was forceful or laidback, spry or gentle, as the Serenade’s many movements required. Always, he was completely musical and completely civilized.

Handling the solo violin work was the Philharmonic’s concertmaster, Glenn Dicterow. He was perfectly competent, if not touched with ideal violinistic or Mozartean grace.

I might say that, by the look of him, Sir Colin enjoyed himself thoroughly – he could barely stop smiling, sometimes grinning. So engaged and engaging was he, he made the “Haffner” Serenade – which lasts about 50 minutes – skip by. It didn’t seem longer than about 48 minutes.