Andris Nelsons’s original instrument was the trumpet (check out the story of his recent duet with Thomas Rolfs HERE), so it’s not surprising that this weekend’s Austrian program pairs Mahler’s Fifth Symphony, where the first trumpet annunciates the opening funeral march, with Third Viennese School composer HK Gruber’s 1999 trumpet concerto Aerial. It’s not a new coupling: Nelsons led the same program — and with the same trumpet soloist, Håkan Hardenberger — with the Berlin Philharmonic in April 2015. As performed Thursday, it made a strong bid to be the highlight of the BSO’s season.

Hardenberger in fact commissioned Aerial, and he was of course the soloist in the premiere, with Neeme Järvi at the 1999 Proms. Gruber himself is not a trumpeter but a Vienna Boys’ Choir alumnus who took up the double bass and played in the Austrian Radio Symphony Orchestra. He’s best known for his 1977 “pan-demonium” Frankenstein!!, and he’s up to similar hijinks in Aerial, where he calls for the soloist to sing in falsetto and play a trumpet note at the same time, to remove slides, to employ a battery of mutes, to switch to a Swedish cowhorn and then to a B-flat piccolo trumpet.

Aerial’s two movements run about 13 minutes each. The first takes its inspiration from the “Done with the compass — Done with the Chart!” line of Emily Dickinson’s “Wild nights — Wild nights!” The poem is worth revisiting:

Wild nights — Wild nights!
Were I with thee
Wild nights should be
Our luxury!

Futile — the winds —
To a Heart in port —
Done with the Compass —
Done with the Chart!

Rowing in Eden —
Ah — the Sea!
Might I but moor — tonight —
In thee!

Thursday’s performance began with twinkling percussion and flute, as if Emily had indeed done with compass and chart and found herself in an undiscovered country. Hardenberger began almost immediately with what Gruber calls “multiphonics,” and his simultaneous singing and playing undermined what he calls the “directionality” of the trumpet. The playing took the form of spooky starbursts, slogans from the beyond. Four minutes into the piece, the first mute came out, and the trumpet sounded mournful and spookier still. After a pair of tam-tam crashes, Hardenberger’s phrases got longer and bluesier. The cowhorn, which he picked up eight minutes in, was even less pitched and directional, though the pristine, wind-like sound and chromatic half-steps he drew from it were quite amazing. He then did some squalling on piccolo trumpet before returning to his regular instrument.

The second movement followed without a break. Headed “Gone Dancing,” it evokes the view from a distant planet of our own Earth as a world without life. That world did appear deserted at first, but soon our view was redirected toward wherever the dancing had gone. Whereas in the first movement Hardenberger seemed to be playing against the orchestra, here he was swinging with it. After essaying some ditzy and galumphing rhythms, with melodic fragments flying everywhere, the orchestra was ready to rumble, and Hardenberger settled into a groove for Gruber’s version of the music of the spheres. The intensity grew; Hardenberger switched back to piccolo trumpet, and at one point we seemed to hear Petrouchka-like trumpet against a Sacre-like orchestra. Still playing piccolo trumpet, Hardenberger signaled the end by leaving his place next to Nelsons and walking upstage right. Facing the piano, with his back to the audience, he gave out a final bleat, and that was that. Call it “Emily’s Wild Night in Eden, Where She Finally Gets To Dance.”

Mahler’s Fifth Symphony limns a simple progression from dark to light, beginning with a military funeral march, in C-sharp minor, and ending with a rollicking rondo in D major. Along the way we get a stormy revolt, an ebullient if mystifying scherzo, and Mahler’s most popular (certainly his most performed) composition, the soulful fourth-movement Adagietto. But musicologists, especially in the wake of Theodor Adorno, continue to wonder whether the symphony’s apparent big yes (in Nietzschean terms) isn’t really a big no. (Donald Mitchell’s 125-page essay on the Fifth is titled “Eternity or Nothingness?”) Or at least whether the triumph of the Adagietto and Rondo Finale isn’t a hollow victory in view of what’s come before. The symphony is actually a big riddle, with clues in the form of allusions to other Mahler works and, prominently in the Adagietto, to Wagner’s Tristan und Isolde. And that’s even before we get to the donkey apotheosis.

The opening Trauermarsch (“In gemessenem Schritt. Streng. Wie ein Kondukt.”) has you off balance from the outset. It begins with the same B-flat trumpet tattoo that in the first movement of Mahler’s Fourth seemed to be signaling a panic attack — and yet it’s in the same rhythm as the first four notes of another famous Fifth, Beethoven’s. The mood, however, is that of “Der Tambourg’sell,” a Knaben Wunderhorn song about a doomed drummer that Mahler composed around the same time as the Fifth (1901–1902). Near the end, right before the timpani tap out that trumpet call, Mahler quotes a phrase from the first of his Kindertotenlieder, “Nun will die Sonn’ so hell aufgeh’n,” a phrase to which he set both “als sei kein Unglück die Nacht gescheh’n” (“as if no misfortune had befallen in the night”) and “Heil sei dem Freudenlicht der Welt!” (“Hail to the joyous light of the world!”). Do those lines suggest a ray of hope?

If so, it’s the only one in the movement. The first trio (“Plötzlich schneller. Leidenschaftlich. Wild.”) is an angry, passionate outburst, perhaps from relatives and friends; the second one is resigned. The onlookers’ emotions can’t slow the procession; Mahler marks the coda “Streng” (“Strict”). The A-minor second movement (“Stürmisch bewegt. Mit größter Vehemenz.”) brings the real storm of rebellion against God or fate. The ascending second theme doesn’t promise much, so it’s a surprise when a massive, redemptive  brass chorale materializes at the climax, and a bitter disappointment when that chorale evaporates into thin air, leaving shards of protest behind.

The Scherzo (“Kräftig, nicht zu schnell”) is where Mahler starts to unmoor us. We’re in D major now — but isn’t that the key in which the symphony is going to end? What’s it doing already here in the third movement? Surely this jolly, robust Ländler can’t be the composer’s last word? And where did it come from? Is it the departed’s flashback to happier days? Or the composer’s attempt to turn his back on the mortality of the first two movements?

After a bit, a shy city waltz shows up, and from then on you have to decide whether the city waltz corrupts the country Ländler or the Ländler introduces the waltz to country pleasures. What does seem clear is that the obbligato French horn theme is nostalgic in the same way the posthorn solo is in the Scherzo of the Mahler Third. It might be the composer’s farewell to the Wunderhorn world of his first four symphonies; it might be our signal that the child of the Fourth Symphony is about to reach puberty. Whatever, the dizzy dance of waltz and ländler goes on. Mahler at one point called this movement “Die Welt ohne Schwere” (“The World without Gravity”), suggesting lightheartedness or thoughtlessness — or both. Perhaps this movement is his big yes and his big no. The youthful Mahler’s literary heroes, Jean Paul and E.T.A. Hoffmann, would have approved.

The Adagietto, too, seems to come from nowhere. In this case, the composer turns his back on the bustle and noise of the Scherzo and takes refuge in strings and harp. The opening phrase conjures the second Kindertotenlieder song, “Nun seh’ ich wohl, warum so dunkle Flammen,” but later on there are unmistakable allusions to the “gaze” motif from Tristan. Dutch conductor Willem Mengelberg recalled that both Gustav and Alma had told him the Adagietto was Mahler’s musical love letter to Alma. There are reasons to doubt this story: Alma makes no mention of it in her memoirs, and Mahler, once he had become director of the Vienna State Opera, was largely limited to composing in the summer. Alma and Gustav started up in November 1901 and were married in March 1902, so if Mahler wrote the Adagietto during their brief courtship, he must have found time during the busy opera season. Still, Alma, herself a proficient composer, would certainly have recognized and understood the Tristan allusion.

A further complication with this movement is the tempo marking: “Sehr langsam.” The usual sense of “adagietto” is “not quite as slow as adagio,” but how does that square with the “very slow” of “Sehr langsam”? Whatever, there can hardly be another piece of classical music that’s seen such a wide range of timings. Mengelberg with the Amsterdam Concertgebouw in 1926 took just 7:15; Bruno Walter in his 1947 New York Philharmonic recording checked in at 7:37. They were Mahler’s friends, so you’d think they knew what he wanted, but eight minutes for this movement scarcely registers as even slow, let alone very slow. Nowadays, timings average 10-11 minutes, but Karajan, Levine, and Abbado have been up around 12 minutes, and Haitink in his 1988 Berlin remake set the current commercial-release record at 13:55. If a conductor can get the movement to sing, time is irrelevant, but it’s obviously more challenging to phrase at a slower tempo.

The Rondo Finale is more ambivalent still, if that’s possible. This one is Mahler’s “Donkey Show,” since it begins by quoting his Wunderhorn song “Lob des hohen Verstandes” (“Praise of Lofty Discrimination”), in which a cuckoo and a nightingale engage in a singing contest, and the donkey judge — chosen by the cuckoo because of his long ears — awards the prize to the cuckoo, whose simpler song is easier to understand. (Raise your hand if you think Mahler had in mind the music critics of his day.) In the midst of the movement’s fugato follies, the Adagietto’s main theme returns, now sped up and sprightly, almost a polka. Also returning is the chorale from the second movement. This time it’s sustained, to the distress of musicologists who complain that it doesn’t develop out of the musical material and anyway, a rondo can be a victory lap but it’s not where you win the race. In a way, this finale is also Mahler’s little joke, again in the tradition of Jean Paul and Hoffmann: epic as satire. What might not be in question is the symphony’s conclusion. The Fifth ends with a cathartic descending thump that has suggested to some the sound of a composer booting a reviewer down a flight of stairs.

Nelsons’s Symphony Hall interpretation Thursday, like the one he gave in the Berlin Philharmonie, was a decided yes. At 73 minutes, it was slightly more compact than the Berlin performance, and all the better for that, though 73 minutes is more expansive than average for the Fifth. Expansiveness is a big part of what I like about Nelsons’s Mahler (and, for that matter, his Shostakovich). It’s a crystalline, chamber-like expansiveness; you get to hear the innumerable details of Mahler’s score — which is especially gratifying when the score is being played by the BSO. It’s almost never sluggish or soupy. And because Nelsons makes the big gestures and gives the music the ebb and flow that Mahler’s hypermarked scores demand, his reading coheres and has shape.

Thursday started with a personalized tattoo from principal trumpet Thomas Rolfs — I’ve never heard the Fifth’s opening fanfare sound so un-rote. That was a harbinger of the delights to come. The French horns were flavorful (rustic but not raw); the strings were delicate and expressive. The march itself had more forward motion than it did in Berlin (where there was a hint of sentiment); the first trio exploded, as it should, and here the trumpets were cutting but still noble. Timothy Genis’s timpani tattoo was stark and well judged; Nelsons’s coda could have offered a smidgen of breathing room (think of how Tennstedt would conclude this movement), but it’s hard to criticize a conductor for abiding by Mahler’s “Streng” instruction.

Nelson’s second movement lacks the “Vehemenz” of some interpreters. Thursday’s reading was stormy rather than frenzied — but it’s the frenzied readings that tend to clot. Here the trombones and tuba were black with rage and despair, and in the rising, consolatory second theme, the cellos re-created, as Mahler asks, the calm tempo of the Trauermarsch. In place of hysteria we got drama. Hysteria isn’t necessarily bad, but in this movement it’s hard to have both.

The Scherzo was afforded room to dance — which is not always the case. Nelsons allowed both ländler and waltz to swing (sometimes together); the waltz, on its first appearance, was extremely shy. Once James Sommerville’s French horn had resurrected that world of lost innocence, the first violins took up the idea (“Fließender, aber immer gemäßigt”) with heartbreaking sweetness. Some scholars see this horn theme as a premonition of death (as the posthorn is in the Third), but Nelsons treated it as Mahler’s wistful adieu to his childhood. (After Vienna, what innocence?) Nelsons’s peroration, in which all the movement’s themes assemble, was a celebration, for better and worse, of what Mahler’s life had become by 1901.

And yet Nelsons’s Adagietto, at a moderate 10 minutes, found another dimension to that life. Conductors so often seem mesmerized by this movement; your choice is monochromatic dirge or monochromatic serenade. But Mahler gives new instructions every few bars, and Nelsons caught the rise and fall of the writing, the swell, the calm. Add in the imaginative phrasing of Jessica Zhou’s harp and the music bobbed like a Venetian gondola. It became a movement where Gustav leaves Vienna behind, where he and Alma have, as the “gaze” motif suggests, eyes only for each other.

As for the cheeky, teasing Rondo Finale, it was no hollow victory but a triumphant return to innocence of a sort. The cuckoo started it off, in a plush descending fourth from solo French horn; then the donkey bray was unmistakable. (In real life, and in Beethoven’s Pastorale, European cuckoos call a descending major third, but Mahler’s cuckoos sometimes call a descending fourth, as at the beginning of his First Symphony, where they’re the good guys.) The return of Adagietto theme was lightfooted and carefree, and Nelsons treated everything with such tenderness and good humor, you could imagine Alma and Gustav as adoring parents, with cuckoo, donkey, and nightingale as their future daughters’ stuffed toys come to life. The chorale emerged not from the thematic material of the movement but from its joyous mood, from the sheer exuberance of the writing. The Rondo Finale has a reputation for being the worst of Mahler’s finales; here it sounded like the best.    

Jeffrey Gantz has been writing about music, dance, theater, art, film, and books for the past 35 years, first for the Boston Phoenix and currently for the Boston Globe.