Roll up, roll up for a circus of musical meaning, a surreal carnival where nothing is quite as it seems, where strange musical machines and even a glittering musical toyshop become an existential journey into the beyond.

Welcome to the world of Dmitri Shostakovich's 15th, and final, symphony.

Composed in 1971 in just a few weeks, the 15th Symphony belongs to the period of Shostakovich's darkest music. By this time in his life, already an ill man, Shostakovich's compositional concerns took a turn inward. The questions the 15th asks are some of the most profound Shostakovich ever posed: about the limits of musical expression, about what musical individuality and personality might be, and about the apparent impossibility of creating symphonic coherence in the late 20th century.

Every bar of the piece demands a variation on the same simple but utterly profound question: what does it all mean? What is that chirruping little tune at the start of the symphony about? Why does Shostakovich quote from Rossini's William Tell in the first movement, from Wagner's Tristan und Isolde and Ring cycle in its last movement? Why does the whole thing end with a coda that on the surface could be a memory of childish things, but is far more likely a musical transliteration of the hum and clatter of hospital machines, the faceless whirring and bleeping that are the grim accompaniments of disease, decline, and death in medical institutions - sounds that Shostakovich was already familiar with at this stage in his life? And why, as Shostakovich surely knew this would be his last symphony when he was writing it, does the piece scrupulously avoid any trace of the bombast and boisterousness of his earlier symphonies?

Dmitri Shostakovich (left) and Benjamin Britten, photographed in 1966.

But let's start at the beginning: this is only symphony ever written to open with a solo glockenspiel. The surface of the flute tune that follows is chirpy and apparently cheery, like someone whistling in the street (though you're unlikely to blithely whistle a tune that pivots around A minor and A flat major). There's a strange second melody in the bassoon, an oddly mechanical bit of patterning in the strings, and a strangely familiar rhythm in the brass, and then Shostakovich quotes Rossini's William Tell overture.

Weird. Yes, Shostakovich has set up a sort of pre-echo of the William Tell tune in some of the rhythms we've heard; but when the trumpets play the tune, it's a shock. So is it ironic? Not really, there's a genuine musical connection, a reason for it being there. A parody? Again, it's not that simple; Shostakovich doesn't frame this moment as a separate kind of discourse from what we've heard so far, this quote isn't in quotation marks. And in fact, I don't actually think this is a quotation at all: what I mean is that the effect of hearing this music at this point in the symphony is so utterly removed from the original function, expression, and associations of Rossini's tune that it becomes, in fact, a totally different object. Instead of infectious operatic cheeriness, we're in a place of existential symphonic crisis. If anything, you hear the disjunction in meaning and context even more precisely because the pattern of the notes is so familiar. Make sense? Possibly not - but these are the kind of labyrinths Shostakovich's symphony leads you into… (Even Shostakovich himself couldn't properly explain the reason for the quotes in this symphony: "I don't myself quite know why the quotations are there, but I could not, could not, not include them," he told his friend Isaak Glikman in a tortuous bit of triple-negativity.)

And that's a clue to the doubleness and ambiguities of this whole symphony. You could describe the atmosphere of this first movement as playful, but if that's true, it's happening on a playground in the middle of a blasted, denuded landscape. The music is set among the ruins of musical meaning, surrounded by broken shards of musical history and Shostakovich's personal symphonic canon, the burnt-out remains of old certainties and delusions.

There are still three movements to come: there's a long slow movement that veers between intimacy and the symphony's only moment of climactic gigantism, there's a shorter allegretto, and a remarkable final movement that quotes Wagnerian emblems of tragedy and death, which allude to Rachmaninov's Symphonic Dances and Shostakovich's own 7th Symphony, that creates a bizarre musical ennui in its meandering string lines – and which ends in a hospital ward, with the percussive rattles and wheezes of those hospital machines. The final sounds of Shostakovich's symphonic canon are impassive, intimate, and empty. They're among the most spine-tingling and chilling sounds in orchestral music. The patient at the end of the piece is, on one hand, Shostakovich himself, as if the composer is asking himself at the end of his life: what was it all about? All that sound and fury, all those symphonies, were they all just leading to this hollow, clacking emptiness? So on the ward too, is the whole notion of symphonic meaning.

Which is all why I think that Shostakovich's 15th Symphony is one of the most profound and prescient of post-war symphonies. A final thought: David Lynch made Blue Velvet heavily under the influence of this symphony. That makes surreal sense…

Five key performances

Valery Gergiev's raw, edgy performance with the Mariinsky Orchestra (above)

Mariss Jansons's brilliantly characterised performance with the London Philharmonic Orchestra

Bernard Haitink and the Concertgebuow's sober and moving symphonic surgery

Shostakovich's son, Maxim, conducts a 15th of unique and searing authority with the London Symphony Orchestra

Vasily Petrenko leads this recent release, part of his highly-acclaimed cycle of Shostakovich's symphonies with the Royal Liverpool Philharmonic Orchestra.

See also

1: Beethoven's 5th

Tom Service introduces his symphony series