Few albums are as big as Pink Floyd's 1973 blockbuster The Dark Side Of The Moon.
Estimated to be one of only four albums to have sold over 45 million copies worldwide, it's spent more than 970 weeks, or the equivalent of over 18-and-a-half years, in the Billboard top 200 album charts in the US, which is a record.
Legend has it that a factory was set up in Germany for the express purpose of printing Dark Side Of The Moon CDs in order to keep up with demand.
The album's mythic nature also contributed to the urban legend it was made to synchronise with the 1939 film The Wizard Of Oz.
And despite 50 years of ever-changing musical fads and phases, the album has endured like few others of its era, continuing to sell tens of thousands of copies around the world each week.
In fact, the album — which has been certified platinum 14 times in Australia — was still in the ARIA vinyl top 20 last week.
So what is it about The Dark Side Of The Moon that has made it one of the biggest albums of the last half a century?
'And if the band you're in starts playing different tunes …'
In early 1968, five years prior to The Dark Side Of The Moon, Pink Floyd parted ways with their frontman and chief songwriter Syd Barrett in a fairly straight-forward manner — tired of his increasingly unreliable and adversarial nature due to a drug-induced mental breakdown, the band simply decided not to pick up Barrett on the way to a gig.
The London band had already brought in Barrett's friend — guitarist/vocalist David Gilmour — to cover for Barrett, who had taken to standing stock-still at gigs or wandering the stage like a zombie without playing a note, if he turned up at all.
The albums following Barrett's departure, while all reaching the UK top 10, were a mish-mash of ideas, styles and recording approaches as the band struggled to find its new identity with bass player Roger Waters as the creative driver.
"After Syd went crazy in '68 and Dave joined we were, all of us, searching, fumbling around, looking, wondering 'where do we go now?', because [we'd lost] the guy that's producing all these songs and was the heartbeat of the band," Waters told the Classic Albums TV series in 2003.
Between 1969 to 1972, Pink Floyd released two soundtracks (More and Obscured By Clouds) and contributed to a third (Zabriskie Point), and put out the half-live/half-studio album Ummagumma.
They also released their UK chart-topping studio album Atom Heart Mother, which Gilmour derided as "a load of rubbish" and Waters called "a really awful and embarrassing record".
Things began to coalesce around their seventh album, Meddle, released in November 1971, which Gilmour called "the moment where we found where we were going".
Where they were going was to The Dark Side Of The Moon.
'All your life will ever be …'
In between their prodigious recording output, Pink Floyd maintained a gruelling touring regimen — in 1972 alone, they played almost 100 gigs, including two North American tours, two European jaunts, and visits to Japan and Australia, with just two months off in between.
When the band finally paused to take a breath and decide what to do next, they reconvened at drummer Nick Mason's flat in London, and Waters laid out his idea for the concept of what would become The Dark Side Of The Moon.
"I remember sitting in his kitchen, looking out at the garden and saying, 'hey boys, I think I've got the answer', and describing what it could be about — all the pressures and difficulties and questions that crop up in one's life that create anxiety," Waters said in a 2003 interview.
Keyboardist Richard Wright told a 2003 documentary that "the stress of touring" directly influenced the themes and concept of the album, while Waters described it as "an expression of political, philosophical, [and] humanitarian empathy that was desperate to get out".
As a result, the album "has some kind of universal appeal in that it confronts a number of major psychological and emotional concerns", as Waters put it.
The songs deal with money, death, time, madness, travel, choice, war, and violence, among other things.
It can also be viewed as an examination of life from start to finish, kicking off with a heartbeat, some screams and the opening lyric "breathe", and finishing with a summation of basically everything you do in life, courtesy of the lyrics of album closer Eclipse.
'And all you create …'
Such universal themes make the album relatable, but part of the album's status as one of the greatest of all time also comes from Pink Floyd's adventurous approach in the studio.
Making the most of then-cutting-edge 24-track technology, which made it easier for them to layer and experiment with sounds, the band used sound effects, tape loops, and interview fragments in between songs to accentuate the themes of the album.
A collection of chiming clocks leads into a doom-laden intro on the track Time, which examines mortality, while a tape loop of coin and cash register sounds forms the basis of the track Money, which is believed to be one of the first examples of a band using a tape loop as a kind of "click track" or backing track for their live playing in the studio.
Rather than write words for a song intended to be about religion and dying, they brought in singer Clare Torry to perform a wordless improvisation on the ecstatic track and album highlight that closes Side A, The Great Gig In The Sky.
State-of-the-art synthesisers combine on the breathless travel-inspired On The Run, while snippets of interviews with the people who were hanging around the studio reinforce some of the themes of madness and violence.
And among it all are some of the most beautiful songs Pink Floyd ever wrote.
Any colour you like
Aussie musician Ash Naylor, best known for his band Even and as a guitarist with Paul Kelly and The Church, said "no matter which way you slice it, Dark Side Of The Moon is just gorgeous music".
"If you like rock 'n' roll music and you like beautifully written songs well executed then this record deserves its place in history," Naylor said.
"In the same way people still talk about Mozart and classical music that transcends the ages because of its sheer beauty. It's the same thing with Pink Floyd — it's just beautiful music."
Naylor said there were many angles from which to appreciate the album.
"As a guitar player, it's a master class in lead guitar," he explained.
"Gilmour, on this and on [follow-up album] Wish You Were Here — the playing is profound.
"His place in the pantheon is well deserved."
He said part of the album's appeal lies in its lyrics and themes being universal yet "not too overly intellectual".
"They're direct and evocative," Naylor said.
"It's also a sprawling record, but it's not overly dense — it's kind of concise, even though it's epic.
"[They're] inventing and recording at the same time — there seems to be a freedom amongst them to experiment.
"But like The Beatles, it's all well and good to experiment but it's always handy having some great songs up your sleeve.
"For people like me that have spent the best part of their adult life trying to become better musicians, that people were making this music in their early 20s, it's just astonishing.
"To have such command of your sound at such a young age, it's quite breathtaking really."
'When at last the work is done …'
Pink Floyd recorded The Dark Side Of The Moon over about eight months in between more touring, finishing the album on February 9.
"I can clearly remember that moment of sitting and listening to the whole mix the whole way through and thinking 'my God, we've really done something fantastic here," David Gilmour said in 2003.
Visual artist Storm Thorgerson gave the band seven choices for the album artwork, and they quickly and unanimously chose the refracting pyramid, which has become one of the most iconic and instantly recognisable album covers of all time.
The Dark Side Of The Moon was released in the US on March 1, 1973, and in the UK on March 16.
Capitol Records' new chairman Bhaskar Menon loved the album and launched an unprecedented promotional campaign — the refracting pyramid was soon featuring in magazines and shop windows around the world.
The first single, Money, wasn't released until May, and by that point the album had already sold a million copies in the US.
It only spent one week at #1 in the US, but has been in and out of the charts ever since — in the mid-2000s it was still selling about 9000 copies a week.
'And every day the paper boy brings more …'
More than a few of those copies are in the hands of Sydney school teacher Darren Powter, who is one of the many avid Pink Floyd collectors around the world.
Powter owns over 100 copies of The Dark Side Of The Moon on vinyl, cassette, eight-track and CD, and "about 900 '[Pink Floyd] records … including singles and solo albums".
"You'd compare me to a stamp or coin collector — I look for the different variations, mislabels, mispressings, and I'm trying to be a bit of an Australian-release completist," he said.
Powter's introduction to Pink Floyd as a 15-year-old was simultaneously banal and life-changing, he explained.
"I was raised in an unmusical family — I think we had the best of ABBA and Neil Diamond's Hot August Night [and that was all]," Powter said.
"I was at a mate's place and he had a couple of cassettes [of Pink Floyd] — Wish You Were Here and The Dark Side Of The Moon.
"I borrowed them and it was the first time I sat down with music and was grabbed by it.
"It wasn't in a dark room with headphones or quadraphonic sound — it was on a crappy little cassette player in my bedroom.
"I was a bit put off [by Dark Side] at first — the first couple of songs are a lot of noises and stuff, but I got to a few songs that grabbed me in the middle of the record, like Time and Money.
"And when it finished I rewound the tape and found those songs again.
"About a week later I played it from start to finish [again and] that was it — I was hooked."
Powter said the album's legacy is connected to the huge number of people it touched in some way.
"It's like Fleetwood Mac's Rumours and Michael Jackson's Thriller — if you don't have it, there's something missing from your collection," he said.
"Those albums have got good songs, but this has the reputation where you've got to play the whole album [from start to finish]."
'The lunatics are on the grass …'
It's not every album that has an urban legend about it, but The Dark Side Of The Moon legacy includes the idea that it was made to synchronise with the classic 1939 film The Wizard Of Oz.
The notion first emerged from a Pink Floyd online newsgroup and was given widespread notoriety in August 1995 by the Fort Wayne Journal Gazette.
It's purported that playing the CD on repeat alongside the movie reveals too many moments that match up for it to be coincidence, such as lyrics and sound effects syncing with what's happening on screen.
The album's producer/engineer Alan Parsons derided the idea as "a complete load of eyewash", Waters called it "bullshit", while drummer Nick Mason called it "complete nonsense", joking that it actually synchronises with The Sound Of Music.
But it's all part of the story of The Dark Side Of The Moon, which turned Pink Floyd from a great band into the biggest band in the world.
They would go on to release more albums, among them the classics Wish You Were Here and The Wall, before Wright, Mason and Gilmour parted ways with Waters in a firestorm of acrimony and lawsuits.
But The Dark Side Of The Moon is undoubtedly the pinnacle of their career and the peak of their powers, with the whole band pulling together towards a common goal, which turned out to be something that spoke to tens of millions of people.
Fifty years on, it's still speaking to people. And it's safe to say the music world will never see an album as ambitious and experimental, yet also as successful, ever again.
