Josef Suk's Asrael is named after the angel of death - but it is not all doom and gloom. It's a tribute to lost love, writes Arminta Wallace

Symphony is a bittersweet kind of word. Being at the posh end of the music spectrum, it's often used as a kind of musical code. Say "symphony" and you're talking instant highbrow, all dark wood and classical gloss and best frocks forward for a night at the concert hall. We know where we are with a symphony. Don't we? Four or five movements, with the slow one nicely concealed in the middle (perfect for a discreet power nap) and a big finish to send you out on a wave of euphoria - without frightening the horses.

Which is all fine and dandy, except that the most consistent thing about the symphonic code is that it's forever being broken. Throughout its history the symphony has been bursting out, boiling over and smashing through every rule in the musical style book. Far from being the best behaved of musical genres, the large scale of the orchestral forces involved in symphonic performance, and the sheer amount of noise they can produce when required, seems to inspire composers of symphonies to tell the kind of human stories which would have the horses fleeing at full tilt.

Such is the story on offer at the National Concert Hall on Friday, when the RTÉ National Symphony Orchestra will play the rarely-performed Asrael symphony by the Czech composer Josef Suk. The piece opens with a sombre cello line which, according to one commentator, depicts the eponymous Asrael - the angel of death - casting a cold eye on life's rich tapestry. "Unfurling his leathery wings, he swoops in search of prey . . ."

Thus begins a titanic five-movement musical battle of opposites - the skittish, fragile, irrepressible life force versus the inexpressible stillness of death - portrayed in a virtuoso and often extremely beautiful piece of symphonic writing which its supporters call a masterpiece.

But if it's a masterpiece, how come we've never heard it? Part of the explanation lies in another story; the story of why the symphony was composed in the first place. A child violin prodigy who entered the Prague Conservatory in 1885 at the age of 11, Josef Suk studied composition with Dvorak, who became his mentor, model and eventually - when the 24-year-old Suk fell in love with, and married, Dvorak's daughter Otilka - his adored father-in-law.

Life was good for the young composer. His own music was gradually becoming popular, and the string quartet which he had co-founded, partly to promote the work of Dvorak and other Czech composers all over Europe, was extremely successful. In 1904, however, Suk was on tour in Spain with the quartet when he was handed a telegram. "Return immediately," it read. "Dvorak dead." In a letter the composer describes his nightmare journey back to Prague, and his fears about how his wife - who suffered from a severe heart condition - would react to her father's death. Badly, was the answer. Within 14 months Otilka had also, as Suk puts it, "departed into eternity".

Small wonder that the angel of death was on his mind. "I think this must be one of the reasons the Asrael symphony isn't often played," says Fred O'Callaghan, a specialist in Czech music who will give an introductory pre-concert talk at the NCH.

"People think it's a kind of mourning symphony and that it must be all doom and gloom. But I don't find it gloomy at all. And from what I've read about Suk, I know he didn't mean it to be. He intended it as a kind of monument to the two people he loved most - a celebration, in a way. I think his first thought was that he wanted to write something that would be worthy of dedicating to Dvorak."

O'Callaghan first came across the work when he listened to late-night concerts from Prague on medium-wave radio, long before the days of Lyric FM or even BBC Radio Three. Listening to Asrael, it quickly becomes clear that Suk didn't just break the rules of symphonic writing - including the familiar landmarks of sonata form - but made up his own.

"The whole sound world of this piece intrigued me," O'Callaghan says. "For years I tried to get hold of a score so that I could study it. I finally got hold of a photocopy when I was in Prague before Christmas. I also saw the original manuscript in a museum. It's amazing. The writing is very clear and regular - no scratching out or anything. Where there are alterations, they're just so neat."

Suk may have been composing under the influence of grief, therefore, but he clearly wasn't overwhelmed by it. Nor, despite the emotional crisis of the last movement - complete with thunderous timpani rolls and fearsome hammer blows from the brass section - does it win out in the end. The symphony finishes quietly, with an "ethereal shimmering" spreading from the harp throughout the orchestra, and a final mysterious, soft C-major chord. The calm after the storm? "Some people interpret it as exhaustion," says O'Callaghan wryly.

"And it's true that Suk has a tremendous struggle to reach the major key ending. It does seem to represent a new dawn, or new hope. Something like that. This was Suk's first experience of death, and he's trying - I think - to find a way to fit it into his life. I think, in spite of the background, that it's a very optimistic piece."

Teamed with Smetana's robustly charming Bartered Bride overture and Dvorak's much-loved cello concerto, Asrael - which celebrates its 100th birthday this year - is part of an attractive all-Czech programme at the concert hall.

The future of the symphony itself, however, is more than somewhat uncertain. They're so expensive to commission and perform that few contemporary composers write them any more - though our own John Kinsella has produced nine, with his Symphony No 7 getting a performance earlier this week as part of the Horizons 2007 series at the NCH. The angel of death, then, hasn't been able to flap his leathery wings over the symphony just yet.

The RTÉ National Symphony Orchestra, conducted by Anthony Hermus, plays an all-Czech programme at the National Concert Hall on Friday, as part of the 2006-7 season, in association with Anglo Irish Bank. The soloist in the Dvorak cello concerto will be Han-Na Chang