The greatest myths surround the greatest rock festivals. As Ireland steadies itself for a last drop of the summer festival wine at Electric Picnic, Brian Boyd on the truth behind outdoor music extravaganzas.

It's not for nothing that Woodstock is the progenitor of the music festival. Everything we now consider an essential part of the outdoor live music experience happened on Max Yasgur's farm between August 15th and August 18th, 1969.

Consider: the organisers didn't allow for so much traffic travelling to the festival with the result that people had to abandon their cars and walk miles and miles to the site; double the amount of people who were expected turned up, meaning most everything on the site was broken down or out of order; the facilities were, at best, threadbare; the ticket price was a rip-off; one of the top bands on the bill went on stage hours late (at 4am) because they were rowing about their appearance fee; some big name bands who were advertised didn't show up and were replaced by acts no one had ever heard of; the promoters of the festival blamed everyone but themselves for the chaos and later ended up in court suing each other; it rained incessantly; everyone was miserable but later described it as the most magical moment of their lives.

In the song Woodstock, Joni Mitchell sings:

"I came upon a child of god

He was walking along the road,

And I asked him, where are you going

And this he told me

I'm going on down to Yasgur's farm

I'm going to join in a rock 'n' roll band

I'm going to camp out on the land

I'm going to try and get my soul free

We are stardust. We are golden

And we've got to get ourselves

Back to the garden"

First of all, Joni Mitchell never came upon a Woodstock punter let alone a child of god on the way to the festival. She was stuck in traffic on the New York State Thruway and never made it anywhere near Yasgur's farm.

Woodstock veterans will still swear blind that they heard Joni sing this song at the festival but it simply never happened.

The song, though, is the perfect encapsulation of optimism over experience when it comes to the rock festival. The poetic irony is that it was written in backed-up traffic. We are Stardust, We are Golden. Try We are Gridlocked, We are Bumper-to-Bumper.

That peculiar neurological state of repressing all that is profoundly disappointing about a rock festival and falsely remembering something stardust and golden instead has ensured the longevity of these events.

Woodstock's self-serving mythology (rivalled only by the Vietnam war in the American psyche) still provides the cultural imperative for millions and millions worldwide to "camp out on the land and try and get my soul free".

The now comically hippy-sounding poster for Woodstock bore the legend "3 Days Of Peace And Music", yet just 12 months later the hippy dream lay in tatters at the Altamont Speedway Festival. But the rock festival as a "happening" had arrived and was to become an inexorable force. The Isle of Wight followed in 1970, then Glastonbury. Now it's a globally ubiquitous: from Big Day Out in Australia to California's Coachella, Japan's Fuji Rock and Denmark's Roskilde.

And just to make things even easier, the travelling rock festival was born: Anger Management, Ozzfest, Family Values, Curiosa (headlined by The Cure) and Lilith Fair will all travel to a big green space somewhere near you.

Surprisingly flexible for a behemoth, the rock festival has survived the death of one of its core values: the counter-cultural impulse.

Timothy Leary's enjoinder to "turn on, tune in and drop out" actually used to be a mandatory mantra for festival goers.

This persisted during the '70's and right up until the previously inviolable link between the festival and "youth" was broken.

It was a sociological prescription of sorts that the rock festival was a rite of passage, somewhere where the young would do their rebellious, druggy, rocky thing before they handed the baton over to a younger generation and went quietly to live in the 'burbs and become squares.

Glastonbury changed everything.

Trek down to Michael Eavis's magnificent Worthy Farm these days and you are participating in an event that is not at as far a remove from the Henley Regatta or Glyndebourne as the vast majority of punters would like to think.

Yes they have the beered-up teens and the weird new age types who still bemoan the end of the bartering system but increasingly now you'll see people arriving in their Chelsea Tractors with their aupairs in tow.

People have been screaming "sell out" at Michael Eavis since the very first Glastonbury in 1970. You're charging in? Sell-Out. You're providing full sanitation facilities? Sell Out.

Glastonbury is one of the most convincing reasons why people no longer feel the need to relinquish the festival experience for simple date of birth reasons. There used to be a time when you were supposed to stop buying records and going to festivals at a certain cut-off-point (mainly because you weren't catered for) but marketing departments soon put paid to that chronological anomaly.

The teenage formation-vomiting rock festivals still thrive but the arrival of the "boutique" and the "target market" festival has entailed a broadening out of the festival goer demographic.

The line-up of these newer festivals betrays their intent. There won't be any rap, metal or fashionable teen indie acts on the bill, it will be something a bit more considered, a bit more heritage, a bit more Uncut/Mojo magazine.

Whether it be the Woodstock generation, or the punk generation, people still have an emotional purchase on music.

Some people might see it as a blip that more people buy tickets to see The Eagles than they do Green Day, but it's not, it's perfectly rational behaviour. More people own copies of Hotel California than American Idiot and box-office receipts don't discriminate between paleo-hippies and brash young bucks.

And as the festival audience matures, so does the experience.

Headbanger lager is replaced by the clamour for soy latte; offal burgers give way to organic platters and the only buzz being had is if people stand up from their chairs too quickly.

For every Oxegen there is now an equal but opposite Electric Picnic. Both are equally valid and both serve what their prospective audiences expect and require. Their co-existence is testimony to how the music industry and the festival industry remain cognisant of shifting trends and changing behavioural patterns. Both are "happenings" that mean different things for different people.

Electric Picnic is the last of this summer's festival wine.

Whether you've been moshing to rap, singing along with Kenny Rogers, air-guitaring to Metallica, or tapping your hush puppies to The Eagles, you've been participating in a musical change for the better. Even if instead of turning on, tuning in and dropping out, you simply dropped off.

The Electric Picnic is at Stradbally, Co Laois from September 1st to September 3rd.