That this performance would speak to us powerfully might have been foreseen by readers of Italy's Il Corriere della Sera. In an interview published on the morning before the concert, Iván Fischer first spoke of his joy at bringing Mahler's Symphony no. 3 to La Scala: a work that had not been heard in the Filarmonica della Scala series for ten years, and one that would allow us to experience the Budapest Festival Orchestra's vast creative resources in all their glory. He ended by meditating on the deep challenges that face contemporary society; challenges that he feels we will ultimately overcome.

A thorn in the backside of Hungary's right wing Orbán administration, Fischer is no passive observer of world events. He has been critical of his government's souring rhetoric, which many interpret as increasingly xenophobic, homophobic and antisemitic. Fischer recently featured in a welcoming concert for asylum seekers alongside Simon Rattle and Daniel Barenboim, which is brave when you consider Hungary's stance on Europe's refugee crisis, and that the BFO is heavily reliant on state funding.

In Italy too, high profile musicians have made their voices heard by the native government – here on the topic of arts cuts, just one of a plethora of social hurdles currently facing a nation undergoing a deep identity crisis. Tonight's performance pitted deep struggle against a picture of faith. It provided one of those rare musical experiences where playing enters in dialogue with the prevailing zeitgeist to produce something momentous.

Fischer painted the opening in deep, seething colours, delighting in the grizzly end of Mahler's spectrum in a picture of chaos. This was an interpretation that enthralled and bewildered in equal measure. The ear was never allowed to follow one train of thought for too long. Rather, it was jolted back and forth between growling horns, sneering marches and the rumble of barely perceptible percussion.

The conductor has worked hard to invest these players with a sense of individualism, through voting rights on repertoire, or strictly non-contractual membership of the orchestra so that players can go away and come back refreshed. Such individualism was in full evidence tonight in this vivid melee of orchestral sections. Passionate commitment percolates right back to the furthest desks. Musicians play as if their lives depend on it.

Such an absence of polished integration was the secret to this performance. Glimmers of cohesion were hard fought, and were all the more rewarding when they finally arrived. Fischer's bullish frame hounded his players, now prodding the oboes, now extracting a lithe, brassy yarn with a treacly gesture. But when the sound coalesced at unexpected moments, we were swept off our feet. Fischer's innovative spacial arrangement of his players here came into its own – double basses lining the back row, timpani bookends flanking either side. Intense listening prevailed. A common sense of purpose would sweep through the ranks. This was a compact, tinderbox unit, that could ignite at any moment.

Had it all been planned, or was this sheer spontaneity? The reality felt like a combination of the two: players knew the roadmap, but were able to follow the whims of a conductor that has been at the heart of all this orchestra has done since its foundation some 30 years ago. In full evidence, however, was that there were the necessary reserves of magic for when the action eventually simmers down.

Time stood still as the fugelhorn solo trickled from the heavens to mingle with the moonlight shimmer below. Soprano Gerhild Romberger may have lacked the required mystery in her delivery of Nietsche's "Midnight Song" when she entered clumsily and under the note. But her robust rendition at least thawed the texture in the build up to the glittering peeling bells of the Chor des Bayerischen Rundfunks and the Coro Voci Bianche dell'Accademia Teatro alla Scala combined.

Mahler's abiding goal was to distill the entirety of the human experience into symphonic form. His Third Symphony was perhaps his most successful attempt to do so. All initial angst has been expended by the end of the work, leaving only ecstasy in its wake. For all of its technical wizardry, it was clear that ardour is what the BFO does best. The Finale ebbed with nobility and poise at first, before the lead cellist took a deep breath for that final climb and dug deep with his bow. Passion erupted from all around – it was a glorious, staggering push to the summit.

"If we play well," Fischer had promised in his interview, "we will bring tears to your eyes." He achieved nothing less through the depth and singularity of his vision. In the midst of despair, the message went, there is a beacon of hope.