Necks and Swans float into the murk and mud of Melbourne

Mahler's Eighth Symphony demonstrated, arguably more than anything else in the history of music, that white comes in many shades. It's a massive, prolonged explosion of blinding light and yet, even when you're blinded by it, you can't help but notice its shifting hues, the ways that shadows, as much as dazzle, go to make up the glare. It's a work that can at first seem pretty overwhelming, too bombastic, just too much noise. But when you get to know it, when you delve into its density, you can see that its blaze is really a million billion different specks of white.

And what Mahler did a hundred years ago in Austria for white, the Sydney based Necks and the New York based Swans did last night in Melbourne for black.

The Necks are a drums, bass and piano trio - but the drums are decked with bells and bits of metal, and the bass is a cello/double bass hybrid, and the piano is hit by fists as well as fingers, and nothing these musicians do conforms to music's usual rules and genres. Their music is always organic - improvised from the tiniest thimble-full of notes and ideas, and growing, always growing, into things bigger than any sum or product of their parts.

But if you can imagine a dark lake where ash and smoke mingle, and where bits of molten rock, black and red, bubble and gurgle, where imperceptible simmers of quitely brushed drums and tinkling piano notes have the savage beat of a disgruntled bass plodding beneath them; if you can imagine stasis and motion fused together so that stillness moves to chaos without you noticing that either of them started or finished; if you can imagine music tremoring beneath you, weaving around you, seducing you and smothering you with its single 40 minute arc of darkness, at first hypnotically fine and sensual and then, before you realise what has happened, impenetrably dense: if you can imagine all of that, then you might have a sense of what The Necks created when they opened proceedings at Melbourne's Forum Theatre last night.

But if you can then imagine that hermetic rock, and you, being pounded to dust by a black fist of unspeakably horrible beauty, of unrelenting manic force, pounding and pounding with titanic moodiness, as if every god and demon of history is collectively pissed off: if you can imagine that, then you might also have a sense of what Swans did when it was their turn on The Forum Theatre stage.

Michael Gira - the creator and centrepiece of Swans - once noted that swans are majestic and beautiful creatures, but with very ugly temperaments; and when you listen to his band, with its droning, pounding, guitars; its pummelling drums, knocking at you from inside the doors of hell; with the mad smorgasbord of unimaginable instruments that Thor Harris plays and the worn drone of Gira's voice, then you see those fierce, splendid birds writ large.

It was a night of loud, very loud music - a night where everything was in a minor key, where chords and discords hammered and hammered into you, and smashed the concrete of your brain. But this was music that grows out of the bowels of humanity - music that has its roots in murk and mud. So, despite its dark grace, it can never pretend to tread lightly.

But that is not to say that this music is monochromatic. Like Mahler's white, Swans' black has many shades. But they're all dark and so, even when Thor swings his hammer into his tubular bells, the shaft of light that streams into the music hits you like an axe. It never comforts you. It never brings you relief.

It was a wonderful thing - as wonderful as it was unexpected - that Michael Gira reformed Swans after some 13 years without them. And to be able to see this phenomenal band on stage, to almost be able to feel the old, regurgitated, black acid of Michael Gira's spit land upon my skin when he sang, was something that I never imagined I would come to experience.

But maybe in a world where we want to be able to so quickly and easily decide who is right and wrong, who is good and bad, it is timely for us to be reminded that ugliness and beauty are never black and white.