The Lexington Symphony joined forces with the Nashua Symphony, the New World Chorale, the Nashua Symphony Chorus, the Boston Children’s Chorus, and nine vocal soloists on Saturday, November 20, for a rare performance of Gustav Mahler’s Symphony No. 8, the so-called “Symphony of a Thousand,” at Lexington’s Cary Memorial Hall. Jonathan McPhee, music director of both orchestras, brilliantly led this colossal undertaking. In his pre-concert talk, he noted that 2010 marks both the 150th anniversary of Mahler’s birth and the 100th anniversary of this symphony’s premiere, which did indeed involve 1,029 performers and was conducted by the composer. My chief reservation about this performance was not performance-related but rather the considerable acoustic limitations of the hall. It is a tribute to the singers, instrumentalists, and conductor that they largely overcame this obstacle in a performance that carried the audience off in a tsunami of ecstasy.

Mahler unusually structured the work in two lengthy parts. The first uses the ninth-century Latin hymn, Veni Creator Spiritus (Come, Creator Spirit); the second sets the final part of Goethe’s Faust, in German, of course. As the conductor noted in his talk, the hymn text seems a humble request for enlightenment in every sense, but Mahler reconfigures it into a huge, impassioned demand. As such, the music makes extravagant demands on the performers, most obviously on the choruses and soloists. The dynamic more often than not is between forte and triple forte, and the tessitura, especially for sopranos, stays cruelly high for long stretches. It was thrilling to hear these choral singers throw themselves into their task with such panache but without sacrificing disciplined ensemble. The same can be said of the orchestra, which largely maintained good balances with choruses and soloists as well as solid intonation in an unhelpful sonic environment.

The calmer spots in Part I, generally where the text refers to the frailty of human bodies, had a salutary contrasting effect. Mahler, having been inspired by an old text, chose to set much of it polyphonically, i.e., in “old” musical forms but using late-Romantic harmonic language. Care was taken to keep each contrapuntal line clear in a way that generated its own frisson of excitement. If the words were seldom clearly audible, it likely had less to do with the choruses’ and soloists’ diction than with the desert-dry acoustics. The Lexington Symphony prudently supplied full original-language texts and translations. The seven soloists of Part I, soprano Elizabeth Keusch, soprano Michelle Trainor, mezzo Marjorie Elinor Dix, mezzo Tania Mandzy, tenor Thomas Studebaker, baritone Steven Scheschareg, and bass Fred Furnari, sang their solos with distinction and, despite a wide variety of vocal types and timbres, mostly formed a cohesive ensemble when called upon to sing together.

If the overriding challenge of Part I is having enough stamina, those of Part II are subtler and more varied. This section is closer to opera with something of a plot line and individual roles assigned to the soloists and even the choruses. After the stunning conclusion of Part I there was to be only a brief pause before commencing Part II, but a violinist had to take some minutes to replace a broken string. (An audience member near me was heard to say, “Only one violinist broke a string?”) Despite the delay, the contrast at the beginning of Part II was very striking: string tremolos, flute, piccolo, and oboe depicted the majestic isolation of Goethe’s “mountain gorges, forest, cliff, solitude.” The choruses entered with deliberate tentativeness, words broken into component syllables, as they negotiated the treacherous terrain.

Pater Ecstaticus entered, foreshadowing the difficult path to divine love, perhaps making oblique reference to St. Sebastian: “Arrows, pierce me . . . lightning, thunder through me, that now the worthless may be cursed, that the enduring star, Eternal Love’s center, may shine forth.” Steven Scheschareg sang with an expressivity worthy of his character’s name. Fred Furnari, Pater Profundus, sang valiantly but was sometimes overmatched by the turmoil of the huge orchestra around him as it described what he sang about: a thousand streams hurtling down in a dreadful plunge, lightning strikes, etc. He did deliver a moving conclusion, however: “O God . . . Bring light to my needy heart!”

A series of treble choruses followed, illustrating the different castes of angels: Angels, Blessed Boys, Younger Angels, and More Perfect Angels. The Blessed Boys were the province of the Boston Children’s Chorus who were regrettably only audible when not in combination with the women of the other choruses. When heard, their sweet sound well reflected their angelic status, and their musicianship and good German were commendable.

At length we heard from Dr. Marianus (aka Faust), sung by Thomas Studebaker who is that rare breed, a genuine heldentenor (heroic tenor). He entered rather modestly in combination with the Younger Angels and Blessed Boys, praising the Queen of Heaven and only gradually climbing to thrilling heroic declamation.

For Part II another mezzo, Janice Edwards, sang Mary of Egypt with devotion, lacking only the lowest contralto projection the part occasionally calls for. Additionally, soprano Jennifer Grimaldi made her quite brief but critical appearance as Mater Gloriosa (the Virgin Mary): “Come, raise yourself to higher spheres!” She floated her one especially high note in seraphic fashion. It was a nice idea to place Grimaldi alone up in the balcony, but unfortunately she exited before Dr. Marianus’ next statement: “Look up, up to the redeeming gaze . . .”

The final “Chorus Mysticus,” giving praise to the “eternal feminine” for Faust’s redemption, began with almost 200 voices singing a cappella in intense pianissimo, one of the great moments in the choral repertoire. It was done stunningly here and laid the foundation for an inexorable immense crescendo that brought to mind Mahler’s description: “the universe beginning to ring and resound.” Bravo to Maestro McPhee and all the performers for surmounting this Herculean labor so convincingly.