One of the most stirring events of the season came late, with an unexpected work and in an unexpected venue. It was the Polish composer Krzysztof Penderecki’s 1983 Viola Concerto (also for cello or clarinet), played by violist Marcus Thompson with the MIT Symphony Orchestra under music director Dante Anzolini. Twenty-seven years ago, Seiji Ozawa and the Boston Symphony Orchestra presented Penderecki’s Threnody for the Victims of Hiroshima, and you couldn’t say he’s been taken up here since. But this concerto is the last thing you’d expect — it’s beautiful and moving, even (naughty word) accessible, without "playing down." At least it was in this impressive performance.

The piece begins with the solo viola in a series of falling two-note phrases: a lament, not quite sobbing, but — as Thompson played it — an expression of a sorrow "too deep for tears," restrained, dignified, yet immediately heartbreaking. Thompson’s "sound" is full, rich, and extremely complex; he has a rhythmic backbone, an edge, even when his tone is most gorgeous and velvety (he wasn’t a student of the great Walter Trampler for nothing). His phrasing "speaks." And he never allows himself to descend into sentimentality or melodrama.

The concerto is in a single movement (about 25 minutes), but it holds your interest as it moves from private quietude through passages of agitation and questioning (Thompson’s viola fluttering over an ominous rumbling of timpani, or sustaining a long tremolo over nervous winds, or his bow moving eerily — scarily — at the bridge of the instrument) and even bitter humor (he turned a little two-note pizzicato into a nasty inversion of the opening lament) before it achieves its final calm acceptance. He built and built the phenomenally complex cadenza as he built the entire piece, never letting up the intensity yet never forcing, in a continuous natural unfolding that humanized the considerable technical challenges.

Anzolini, who next year will be taking over the New England Conservatory Orchestra, guided the superb MIT players through the tricky Stravinskyan rhythms, the emotional swerves, the kaleidoscopic changes of color and texture. This could have turned into an orchestral showpiece, but he never let you forget that his magnificent soloist was the true center of attention.

IN 1996, DAVID HOOSE AND THE CANTATA SINGERS gave the Boston premiere of John Harbison’s Emerson, a two-part setting for double chorus of passages from two Emerson essays, the famous "Self-Reliance" and the little known "Compensation." At his latest concert, as in 1996, Hoose programmed the Harbison twice, this time alternating Emerson’s philosophical inquiries with the spiritual explorations of Brahms, Schütz, and Bach (the great Lutheran cantata Ein feste Burg ist unser Gott) — composers Harbison draws from and responds to, both in theme and in technique. Harbison’s program note focused on the shared devices of counterpoint, symmetry, and inversion. The theme of Emerson is how to live fully and bravely in the world, in the present, in contrast to the older composers, who looked to God for help.

One of Emerson’s most striking moments, in the passage about roses ("There is no time for them. There is simply the rose."), has two simultaneous approaches, parallel and contrasting: a broken, staccato, monosyllabic hesitancy, each word sung separately, a note at a time, while a sustained, unbroken lyric line blossoms into a complex, all-embracing chord on the word "rose." I loved the way the luminous musical "droplets" dropped into the passage about the drop of dew (in the Brahms motet they performed, O Heiland, whose text is from Isaiah, the dew comes from Heaven), and the oracular expression of awe and discovery in the final, repeated "Thus is the universe alive." Throughout, only two instruments, cello (Beth Pearson) and bass (Deborah Dunham), join — or, rather, burrow through — the choruses, like Dylan Thomas’s "force that through the green fuse drives the flower."

Emerson is brief but demanding. The repeat was quite a bit more together — but then the chorus had just sung the trickier and more varied Schütz, the parable of the sower, from Luke, about the seed that bore fruit only when it fell on good ground. The moral: "He that hath ears to hear, let him hear!"

HOOSE IS ONE OF THE RARE MUSICIANS whose interests in the past and in the present are equal. He was the guest conductor for the most ambitious work in the final concert of this tenth-anniversary season of the Auros Group for New Music: Peter Child’s 1984 chamber opera based on Samuel Beckett’s radio play Embers, which capped a Beckett evening that began with a rare screening of his 1964 silent film, Film, directed by Alan Schneider, in which Buster Keaton embodies the archetypal Beckett character ("hastening blindly along sidewalk, hugging the wall on his left, in opposite direction to all the others"), and which gives us, despite moments of hilarity, the unflinchingly tragic side of the Keaton character, his intense and perhaps fatal desire to be alone in the world — unmistakably himself even though we see him, until the very last frames, only from behind.

Embers is a complex piece, largely a monodrama à la Krapp’s Last Tape, but with the main character’s wife also playing an important role. Henry is trying to connect to his father, a suicide; Ada isn’t helping. Henry is a writer, and his thoughts as he walks by the sea are hard to separate from his story about a man and his anæsthesiologist friend. Child’s intricate scoring (beautifully played here, and eloquently conducted) suggests the sea in its ever-shifting moods. Or Henry’s own mindflow. Baritone David Ripley, repeating his premiere performance of 17 years ago, was in sturdy voice and gave himself wholeheartedly to this role’s extreme vocal demands (ranging from spoken declamation to falsetto), though the minimal staging by MIT’s Michael Ouellette wasn’t enough to help him create a vividly focused character. Perhaps any staging would distract from the words. Unlike Krapp rewinding his tape, Henry has nothing to do but think. Soprano Janna Baty, however, waiting patiently in silence for nearly half the opera, conveyed meaning, nuance, and a consistent character in every note of her brilliant voice, and in her smallest gesture.

Beckett’s language is a kind of verbal fugue. It doesn’t need additional music, which doubles the length and stretches the timing. Child’s opera has the large dramatic turning points, but despite its beauties, it rather smoothes out the moment-to-moment quicksilver of Beckett’s tone, in which every phrase seems to be an emotional contradiction of the one before. The setting is very sympathetic to the singers, but no opera exists in which every word comes across, and in Beckett, every syllable counts.

The Auros program also included Quad, Beckett’s late (1982) non-verbal piece for four hooded dancer-walkers (precisely performed by young persons from the Acton School of Ballet), each marking out and moving through an imaginary square — while avoiding its center — to the improvised drumming and/or chiming of four percussionists. The one non-Beckett work was John Heiss’s Fanfare for Auros’s Tenth Season (2002) — the most wistful fanfare I’ve ever heard, and performed with great tenderness and color by Auros artistic director/flutist Susan Gall, clarinettist William Kirkley, pianist Nina Ferrigno, violinist Sarah Thornblade, and cellist Jennifer Lucht.

THE PRO ARTE CHAMBER ORCHESTRA’S usual world premiere was a wonderful one: Marjorie Merryman’s gorgeous Windhover Fantasy, written, as she describes it, during the days immediately following last September 11. "My mind kept turning to images of flying (flying away from tragedy, airplanes flying towards disaster, souls flying up from the ruins)." Her title refers to the small falcon immortalized in Gerard Manley Hopkins’s great sonnet, "The Windhover," which is dedicated "To Christ Our Lord." It’s an image of buckling under the pressure of the wind and the ecstasy of sacrifice and transcendence. Merryman’s eight-minute piece captured the hovering of the bird with James Bulger’s wreathing oboe rising out of the encircling strings. An arpeggio, beginning in the tonal depths, floats up into the air. Passages of increasing urgency (heroic horns and timpani) alternate with moments of mysterious fragility before the bird flies away to the quiet trilling of flutes. Simple devices, really — but a memorable, moving piece that ought instantly to enter the concert repertoire.

The other works were Mozart’s Clarinet Concerto and Posthorn Serenade, which received delightful if not impeccable performances under the light hand of Isaiah Jackson. David Shifrin played the obsolete basset clarinet Mozart wrote for (using an instrument he helped make). It was a treat to hear the lowest notes where they belong, at the bottom of the scale (a modern clarinet has to transpose them into an upper octave). Shifrin’s abrupt descents into the "chest register," and the haunting pianissimo recapitulation in the slow movement, were his best moments in a skillful if not especially soulful performance.

Mozart recycled five of the seven movements of his Posthorn Serenade into a symphony and a sinfonia concertante, but the serenade itself remains the richest of these works, with its sudden tacking from majestic slow introduction to lively allegro, from enchanting rondo (with Ann Bobo’s sweet flute and Bulger’s subtle oboe) to mournful andantino (the piece was composed at the time of Mozart’s mother’s death). Thomas Haunton had some trouble launching the famous posthorn solo, but once he did, it really galloped away.

BARBARA COOK was back at Symphony Hall, mainly reprising highlights from her April Celebrity Series Sondheim concert, for an Evening at Pops (to be telecast later this year). She seemed in even more bountiful voice. "Send In the Clowns" was more moving for being more a monologue than an aria (the full orchestra helped), though the syrupy arrangement for "Losing My Mind" and Keith Lockhart’s fast tempo compromised one of Cook’s most heartrending numbers. It was especially good to hear again her unamplified "Anyone Can Whistle," her exquisite encore in April, and this time with no outbreak of cellphonus interruptus.

This concert also marked the solo debut of the BSO’s newest member, young Romanian cellist Mihail Jojatu, who’s just completing his degree at Boston University. He played Haydn’s D-major Concerto with perfect intonation and quiet elegance, though without much trace of, say, Yo-Yo Ma’s incandescent phrasing. Lockhart opened the evening with a coarse and bottom-heavy Figaro Overture, but in the Haydn his stylish accompaniment couldn’t be faulted.