I was never one of Led Zeppelin's biggest fans, but one track that always got to me was the last on their fourth album, a haunting, deeply ominous version of Memphis Minnie McCoy's When the Levee Breaks, writes Fintan O'Toole.
The song itself dates from the 1927 Mississippi floods, when 13,000 black people were left stranded on the levees at Greenville, Mississippi, where they were starved, abused, forced into slave labour and, in some cases, raped or murdered. It has the raw power of a cry from the depths:
If it keeps on rainin', levee's goin' to break
If it keeps on rainin', levee's goin' to break
And the water gonna come in, have no place to stay
Well all last night I sat on the levee and moan Well all last night I sat on the levee and moan Thinkin' 'bout my baby and my happy home
The sense of abandonment is immediate and specific, but also universal and existential. This is the song of a people who knows what it is like not to be given a damn about. And how long can it be before some rapper - perhaps Kanye West, whose blunt anger burst through the feel-good charity of a Red Cross fundraiser at the weekend - releases a new version?
Disasters strip away facades and expose the bare structures of a society. The waters that hid the streets and buildings of New Orleans, making the surface of the city invisible, also revealed the underlying nature of a troubled country. When America looks at the huge expanse of filthy, fetid water that has drowned New Orleans, it becomes a mirror in which it finally sees the scars on its own face. The scars of poverty, of racism, of ideological zealotry, of public corruption and of environmental degradation, usually concealed by a cosmetic media, become visible.
And this time there is nothing to deflect the gaze. There are no communists or Islamic terrorists to take the blame. One of the most mordant commentaries on the politics of this disaster is Nick Newman's little cartoon in the Sunday Times of an official showing George W. Bush a picture of an Old Testament God: "Here's the bearded religious fanatic responsible, Mr President."
Since blaming God might not go down too well with Bush's fundamentalist base, and since even Karl Rove would be hard put to pin this one on Cuba, it is hard to distract attention from the truth.
What is revealed, of course, is the bloody obvious. The puzzlement in the voices of American reporters as they described the scenes in New Orleans as being like something from the Third World brought home the extent to which America has been fed a distorted version of itself. The US has always had a Third World within its First World. It is the most unequal society in the industrialised world.
New figures from the US Census Bureau show that 37 million Americans now live in poverty - more than the population of California. Thirteen per cent of the population, 18 per cent of children and a quarter of all blacks live in poverty. Being poor in America means having limited access to healthcare (46 million people have no health insurance), substandard housing and poor nutrition. Ill health is endemic: over a 10th of the population of Mississippi has diabetes. And these people are increasingly ignored. The abandonment of the poor of New Orleans made literal and concrete a truth that has been obvious to anyone who is not blinded by the myth of a land of universal opportunity.
The disaster brings these people to the surface and makes their quiet abandonment noisily apparent. It also gives a dramatic immediacy to long-running but generally ignored realities.
There's the chicanery that has allowed the vital flood plains to be handed over to developers. The right-wing attacks on "big government" that have left vital infrastructure to moulder. The crony system of governance that means that the Federal Emergency Management Agency is run by a man whose main experience is in organising horse shows, but who is close to one of Bush's key election organisers. The obsessive neo-con quest for world domination that diverted resources from preventing a predictable disaster to the so-called war on terror and ensured that much of the military capacity required to cope with it was in Iraq. The smug, folksy rhetoric of a president who reaches for empty clichés about rebuilding for the future while desperate people are howling for help.
The levee holding back these realities from America's self-image has broken now. Delusions of omnipotence that have been brutally exposed in the disaster of the US invasion of Iraq must surely be swept away on the overwhelming tide of indifference and incompetence that inundated the poor of Louisiana, Mississippi and Alabama.
Big government is exactly what the people of New Orleans needed and exactly what was denied them. The values of mutual commitment, collective investment and public service have been left high and dry for too long. Perhaps, from the low, wet places, they will re-emerge.