"The end" – the conclusion to every fairytale. These two little words appeared on the Black Sabbath website this week without any elaboration.

That the band have split up is common knowledge – they played their last ever concert in their native Birmingham last month – but this succinct missive would appear to rule out any chance of one-off shows as singer Ozzy Osbourne has hinted or a studio album as guitarist Tony Iommi told The Irish Times in January.

Black Sabbath were their own fairytale – four unfashionable lads playing unfashionable music from an unfashionable suburb (Aston) of an unfashionable city who conquered the world.

All great bands are miracles. It just so happened that a dyslexic petty thief with a voice met a guitar genius who was undeterred by losing the tips of his fingers in a sheet metal accident.

They met a bass player, Tony "Geezer" Butler, with a lyrical sensibility haunted by his Irish Catholic upbringing in Birmingham, and a drummer, Bill Ward, who had the deftness of a jazz musician.

Black Sabbath’s hard-edged blues was truly original. They inadvertently and however much they protest to the contrary, invented heavy metal with the first chord on their first song of their first album.

In that song, also entitled Black Sabbath, they resurrected the diabolus in musica chord, a chord so sinister sounding it was banned in the Middle Ages. This musical experimentation with chords and unusual scales has been the hallmark of heavy metal since then.

Without Black Sabbath there would be no heavy metal, hard rock, grunge or the harder edge of indie. Without their influence, the musical landscape for us hard rock fans would be as beige as it is for everyone else these days.

Every major artist that dies, every major act that splits up is a reminder of the passage of time.

Contributing to last year's annus horribilis were the deaths of David Bowie, Leonard Cohen, George Michael and so many artists who were the soundtrack of so many youths.

For us metal fans, the death of Motorhead’s Lemmy in December 2015 was that melancholy moment. He was the living, breathing personification of everything that was and is exhilarating about heavy metal. Heroically, he managed, despite a lifestyle of ceaseless debauchery, to get to 70 and then, as if exiting the stage triumphantly and on his own terms, died two days later.

In mainstream music, there is always another sensation along. "Every generation throws a hero up the pop charts," Paul Simon once observed.

But, in heavy metal, there are no acts of the calibre of Black Sabbath coming along and, even if there was, the music industry has changed so much that they would never be given the opportunity to make the impact that they did.

As Slayer guitarist Kerry King pointed out recently, Tony Iommi inspired him to take up the guitar but where are the guitar heroes of the 21st century? Is there a single household name to rival a Jimi Hendrix, an Angus Young or a Slash who made their bones in the last century?

There still great music being made in heavy metal, but the end of Black Sabbath is also the end of an era. Guitar-driven rock music has lost its preeminence. It is hard to conclude otherwise but that its best days are behind it.

Still, those of us who grew up in the eighties and early nineties were lucky we had it so good when rock ruled the world. Do not ask for whom the bell tolls, it tolls for our youth.