If there’s an Oedipus or a King Lear of symphonies, it’s Gustav Mahler’s Sixth, the "Tragic." Big, black, and cathartic, with a "fate" rhythm, a recurrent A-major chord that immediately deflates into A minor, and a pair (or perhaps trio) of hero-felling hammer blows, it follows Sophocles and Shakespeare in calling the universe into question. Wilhelm Furtwängler labeled it "the first nihilist work in the history of music." Bruno Walter argued that it "ends in hopelessness and the dark night of the soul . . . the ‘other world’ is not glimpsed for a moment." Leonard Bernstein described the Finale as the "catastrophe of homo sapiens himself."

Lenny was being his usual hyperbolic self: that Finale might affirm the mortality of humankind, but it doesn’t invent the atom bomb. And someone must have torn a few pages out of Bruno Walter’s score, since in the opening Allegro, the soldier in his march with love and death goosesteps into the Garden, a pastoral Paradise garbed in the remote (from A minor) and redemptive (Beethoven’s Eroica Symphony and Emperor Concerto, Mahler’s own Resurrection Symphony) key of E-flat major. Mahler’s Sixth is his "Supernova" Symphony: it does blow itself to bits (in the process spewing much controversy), but not before pealing forth wave upon wave of cacophonous, exultant Creation.

This is also Mahler’s most classical symphony, the life of a star expressed in yin-yang expansion and contraction. The panoply of percussion instruments includes timpani, bass drum, snare drum, triangle, cymbals, harp, celesta, xylophone, glockenspiel, tambourine, tam-tam, deep (church?) bells, cowbells, holzklapper, birch switch, and that hammer, from which Mahler wanted a dull sound, like the thud of an ax. (A contemporary cartoon shows the composer holding his head in dismay and saying, "Dear God, to think that I should have forgotten the motor horn! Well, I’ll just have to write another symphony.") But those eruptive forces give voice to an Aristotelian unity of matter, as the symphony’s initial motifs morph and evolve like a star going through phases. Throughout Mahler evokes the atmosphere of his Kindertotenlieder ("Songs of the Death of Children"), which he finished in 1904, the same summer he completed the Sixth; and in fact the cadential figure from the first of these songs, "Nun will die Sonn’ so hell aufgeh’n," is echoed in the Andante. Just as the Kindertotenlieder hover between sorrow and salvation, so the symphony teeters between its apparent A-minor fate and the hope of transforming that key into A major or else escaping into E-flat major.

The A-minor march of the Allegro energico, ma non troppo ("energetic allegro, but not too much") also alludes to doomed figures from a Mahler song cycle, in this case the soldiers of "Revelge" ("Reveille") and the drummer boy of "Der Tamboursg’sell" in Des Knaben Wunderhorn ("The Youth’s Magic Horn"). But innocence has given way to industrialism (perhaps it’s no accident that the symphony premiered in Essen), and though this juggernaut is, like the marches that begin Mahler’s Second, Fifth, and Seventh Symphonies, fueled by the composer’s characteristic dotted rhythm, it’s driven and dogged-cynical like nothing else Mahler wrote, moving in lemming lockstep until brought up short by a moody, melancholy chorale that shimmers like a vibrating string. This is followed by a rhapsodic F-major melody that the composer’s wife, Alma, tells us was her husband’s attempt to depict her in music.

These three elements ignite not just this first movement but the entire symphony, love and death mediated by mystery. The battleground, though, is that dotted rhythm, which in Mahler always propels us toward the beyond (God or nothing): it underlines the undotted chorale and infiltrates the Alma theme. Mahler’s martial/marital mix dissolves into E-flat paradise, where celesta and cowbells celebrate the harmony of the spheres and the Alma theme is transfigured, eventually getting undotted. This can’t last; ordinary time resumes, along with the march. Yet in the coda it’s the Alma theme that soars, joined by a theme borrowed from Liszt’s E-flat Piano Concerto that undots itself and erupts in noisy, triumphant, A-major joy.

The Andante and the Scherzo attempt to sustain that mood. (Whether the Andante should come before the Scherzo or vice versa has been a matter of debate for the past 96 years — see "Order, please," opposite.) The Andante might logically start in celestial E major (the key of the vision of Heaven with which Mahler’s Fourth Symphony concludes), but it manages only E-flat, hopeful that its redeemer liveth. Like the slow movements of Beethoven’s Ninth Symphony and Mahler’s Third and Fourth, this is an encounter with the Burning Bush, the two primary themes impaled on the thorns of dream and doubt. The E-flat episode from the Allegro was all transcendence; this Andante, even with its celesta and cowbells, is all immanence, and after glancing at A major it tries to ascend into E major, as if earthly paradise were not enough. Its failure sends us back to A minor: the Scherzo juxtaposes an even fiercer version of the opening march with an "Altväterisch" ("old-fashioned") F-major Trio, which hops from 4/8 to 3/8 to 3/4 while attempting to resurrect a more gracious era, and then a spooky second Trio in F minor with a rising woodwind arpeggio and dancing-skeleton xylophone. It ends in broken rhythms, the arpeggio rising into nothingness.

Or into the Finale, where it becomes part of the primordial soup out of which this gigantic movement forms. A variant of the radiant Alma theme begins in C minor (aiming to emulate Mahler’s Resurrection Symphony, which begins in C minor but in the end is redeemed into its relative major, E-flat) and swirls upward before falling into the dotted rhythm and getting cut off by the A-major/minor motto. No easy Apocalypse in this movement. Thematic fragments ghost by in A minor and C minor, but it’s A minor that wins out when the movement proper kicks into gear. Death march, mystery theater, and love theme collide and combine as this star movement tries to fuse hydrogen into helium; twice in the development jubilation takes hold, but each time it’s dragged down — like Faust, or Don Giovanni — by the dotted rhythm of mortality; and the defeat is underscored (though not caused) by the first two hammer blows, at bars 336 and 479. This star does not want for fuel: the recapitulation continues to dream of E-flat, and when that fails it jumps into A major and marches defiantly, twice steamrollering the hitherto traumatic major/minor motto. Paradise reasserts itself, and at the end Mahler’s chthonic trombones annunciate the primary theme in rising waves that then drop — infected by the dotted rhythm — through an A-major scale. This shuffling off of our mortal coil expects to look God in the face by descending to an A-major chord; instead — in one of the most horrific moments in all of music — it lands on a naked, tam-tam-shattered A as the key signature changes to A minor, no God, no answer. Which may explain why Mahler deleted the third hammer blow: coming at bar 783, 10 measures after the catastrophe, it’s redundant. The supernova has become a neutron star, a black hole from which there’s no escape. Tragic? Perhaps. But in the process it has exploded with angelic exhilaration. And the bleak coda subsides into the void from a human point of view. God might see all this differently.

NOT MANY ARTISTS ask such questions — which is why it’s an event to have new recordings of the Sixth by conductors of the stature of Michael Tilson Thomas, Michael Gielen, and Benjamin Zander. All three follow the International Gustav Mahler Society’s Critical Edition in taking the Allegro repeat and placing the Scherzo before the Andante. Tilson Thomas and Gielen give us the two hammer blows called for by the Critical Edition; Zander, who believes that the third hammer blow should be reinstated, lets you hear it both ways. Zander arranges his first and second violins antiphonally, as was Mahler’s practice (actually it was standard practice before the 20th century); Tilson Thomas and Gielen do not. All three performances exceed 80 minutes, so none fits on a single disc. Tilson Thomas provides no filler; Gielen gives you a look at where Mahler was going, in Alban Berg’s Drei Orchesterstücke, and at where he came from, in the Andante from Franz Schubert’s unfinished Symphony No. 10. Zander fills out his second disc with the original (three hammer blows) and the revised (two) version of the Finale, and he throws in a 79-minute third disc on which, as is his practice with his Philharmonia/Telarc Mahler releases, he talks about the symphony; the package sells for the price of one CD.

Taken from live performances last year in the wake of the September 11 attacks, the San Francisco Symphony release has no ambiance, and no presence unless you boost your playback level to the max. Its other shortcoming is Tilson Thomas, who telegraphs every transition with a big ritardando. The Alma theme in the Allegro is mannered and sentimental; on the other hand, the critical woodwind phrases from the bass clarinet in the pastoral section (12:36 and 14:41) are tossed off. The "Altväterisch" Trios in the Scherzo are slow and stiff; the Second Trio opens with a distorted phrase from the oboes and B clarinets (5:19), and the xylophone is backward. The Andante drags self-consciously, the cowbells are backward, and the big E-major climax at bar 154 (13:06) doesn’t move forward; then there’s a huge unmarked ritard on the first violins’ high C in bar 192 (16:09) followed by three seconds of dead silence. The Finale pulls out all the stops with the first appearance of the motto motifs at bar 9 (0:22) and has nowhere to go for the next half-hour. Perhaps it’s not fair to hold Tilson Thomas responsible for performances that may have been mesmerizing in the hall; on disc, however, it all borders on melodrama.

Michael Gielen delivered thoroughly modern — but not mechanistic — Mahler in his previous recordings with the SWR Symphony Orchestra of Baden-Baden and Freiburg (Nos. 2, 3, 4, 7, and 9), and here too he gives the 21st century a human face. The Allegro is more heavy than quick, the Alma theme surprisingly free and heartfelt — even the Liszt theme swaggers. What goes wrong is the chorale theme and the pastoral section, both being treated as transitions. The Scherzo, thudding but not scary, goes at the same tempo as the Allegro (108 bpm), and the Andante (96 bpm) is hardly slower. And in the Finale, the march themes aren’t savage and the Alma material isn’t sweet (though there’s some lovely string phrasing at the 17-minute mark, in the middle section of the development). Like Tilson Thomas, Gielen doesn’t fight the dotted rhythms in the coda but goes gentle into that good night.

As for Boston Philharmonic music director Benjamin Zander, his Philharmonia Mahler cycle (Nos. 4, 5, and 9 so far) has elicited critical respect if not hosannahs, but this Sixth (due out this Tuesday, August 27) has already drawn unfriendly fire from David Hurwitz on the Classics Today Web site. Hurwitz makes light of the Philharmonia as a Mahler orchestra, pointing to what he calls weak trombones, tuba, and lower strings — and it’s true that Zander’s Telarc Mahler hasn’t had the same strong bottom that you hear in his live Boston performances. (Whether the orchestra or the recording is responsible is another matter.) Still, Zander’s 112 bpm for the Allegro mediates nicely between heft and speed, and the trombones that enter at bar 15 (0:32) are alive and kicking. The chorale (2:09) is hushed, a magnum mysterium; the Alma theme rivals Gielen’s in its tenderness. And the pastoral section has no peer. How you do this depends on whether you view it as just another memory, a dead time from the past, or as a moment out of time, an intimation of immortality. Zander stands back in awe, allowing the major/minor motto in the horns at 13:01 and the trombones at 13:23 to emerge transcendent from the stillness; there are wistful touches from the bass clarinet and the solo violin, and from 15:15 on you can hear every oscillation of the background strings. And if in the coda the "molto ritardando" that Mahler asks for as the Alma theme climaxes is not very "molto" (25:08), it makes its point.

The rest doesn’t quite reach this level. Starting the Scherzo at a fast 132 bpm, Zander distinguishes it from the Allegro (Tilson Thomas and Gielen are less effective), but except for the B clarinet at 3:28, it doesn’t snarl, and the "Altväterisch" Trios, at almost the main tempo, don’t have much old-fashioned feel. The Andante is bereaved and beautiful, with some flowing string playing at 2:44, but the cor anglais that introduces the second subject at 1:49 is oddly recessed, there’s what sounds like a telephone ringing at 8:15, and though Zander conveys the pain of the second subject when it breaks back in at 11:33, there’s not much release (or cowbell clatter) in the climax at 12:41. The Finale starts uncertainly with weak brass for the opening major/minor motto and perfunctory phrasing from the bass tuba and then the A clarinets, and it never quite finds its footing, the long introduction not moving forward where Mahler asks it to and the movement proper not opening up to the Alma material or the hammer-blow climaxes. The coda, as in so many Sixths, seems an afterthought, the dotted phrases tight and unresisting.

Zander’s treatment of the hammer blows and his bonus disc have also come under fire from David Hurwitz. Mahler added the hammer blows after finishing the Finale, at bars 336, 479, and 783 (and possibly also at bars 9 and 530, but if blows originally existed at these bars, they were removed before the Essen premiere). When he revised the symphony in the summer of 1906, he expunged the one at bar 783. Alma, not always the most reliable witness, describes them as the three hammer blows of fate and states that Mahler deleted the third one because he was superstitious. I suspect rather that Mahler realized it was parallel to the two he had already removed; in any case, Zander offers both versions of the movement: with the third hammer blow (plus bars 783-789 from the original orchestration) and without. Hurwitz considers this an indulgence for the sake of seven bars whose orchestration is practically identical; he also chides Zander for directing the bonus disc to neophyte listeners. I do wish that these "lectures" would address a more knowledgeable audience, but that’s a marketing decision; otherwise, the answer to Hurwitz is that the second version of the Finale or the bonus disc are both gratis.

MAHLER’S EXISTENTIAL QUESTIONS have elicited some eschatological responses. On his Deutsche Grammophon recording with the Vienna Philharmonic, Leonard Bernstein unleashes both Gustav’s rhythmic fireworks and his bestiary of sound. Klaus Tennstedt with the London Philharmonic (EMI) has an old-fashioned, almost Jean Paul way with this music (the author of "Report of the Dead Christ from the Beyond That There Is No God" would surely have appreciated the Sixth). John Barbirolli with the New Philharmonia (EMI) phrases weight into meaning; Giuseppe Sinopoli with the Philharmonia (DG) is slower still, deconstructive in a constructive way. And former BSO percussion wunderkind Harold Farberman with the London Symphony (Vox) has an unforced manner, brilliant brass counterpoint, and easily the best cowbells on a two-disc set that sells for about $12.

These performances enjoy a sense of space that modern digital recording seems unable to duplicate. Along with a flat acoustic, Tilson Thomas’s Sixth suffers from liner notes that are run-of-the-mill. The analysis of the symphony that David Hurwitz wrote for Michael Gielen, on the other hand, belongs in the Liner Note Hall of Fame. The Berg and Schubert pieces that fill out the Hänssler set are another bonus; the Drei Orchesterstücke were composed in 1914 with the Sixth in mind, so they represent a kind of epilogue. Objective but not impersonal, Gielen’s Mahler is a good choice for fans of Claudio Abbado. As for Zander, his reading of the Allegro stands with Tennstedt’s as the most moving I have heard (out of some 50), and his set is priced as a single disc, so it’s shame the Finale isn’t more cogent and characterized and the sound isn’t better. Still, that opening movement belongs on every Mahler shelf — it sheds new light on Gustav’s dark star.