We are all so inured these days to the business of rock festivals - sponsored, multi-generational, beamed into our living rooms - that it's difficult now to imagine the tribal excitement and trepidation felt by people as they swarmed into New York's Catskill mountains for the Woodstock Music and Art Fair on a long hot weekend in August 1969. Sixty thousand hippies were expected at the event; at least 350,000 showed up, most looking for some kind of communal climax to the 60s rock dream, soundtracked by (most of) the leading lights of the London/LA/San Francisco/Greenwich Village revolution.
The name - the town itself was 70 miles away - has become a byword for the collective celebration of music. The event against which all other rock gatherings are measured, Woodstock has additionally been filtered through Michael Wadleigh's eponymous three-hour hit film, recently boxed up and reissued with two new hours of footage. We know Woodstock and yet we don't know it.
Staged two years after Monterey Pop first signalled that rock'n'roll was going to be a big open-air industry, Woodstock remains The Big One. It is where the radical rhetoric and chemical chaos of the 60s reaches fever pitch.
For the best part of 40 years, the official audio documentation of Woodstock was confined to two albums/CDs, both replete with highlight numbers by the festival's biggest acts: Hendrix, Janis, Sly, CSNY, the Who, Joe Cocker, Santana, Richie Havens et al. Now we have a six-CD box, adding to the previously released tracks not only music by such lesser lights as Tim Hardin, the Incredible String Band, Keef Hartley, Bert Sommer and Quill but previously unfamiliar stage announcements about blue acid, asthma pills and insulin. Even so, the box represents only about a fifth of the music actually performed at Woodstock.
There are 77 tracks here. Beyond the previously released peak moments you should already know - Jimi's Star-Spangled Banner, Sly's I Want to Take You Higher, Santana's Soul Sacrifice - Woodstock 40 features Cocker hollering Dave Mason's rock'n'soul classic Feelin' Alright, Janis Joplin tearing the innards out of Ball and Chain, and the Grateful Dead's 19-minute micro-trip Dark Star. Not to mention Max Yasgur - the Michael Eavis of the story - thanking "the kids" for "proving something to the world".
Were those kids "stardust and golden", in Joni Mitchell's famous phrase, or were they the bewildered inhabitants of a virtual disaster zone? Whichever it was, listening to Woodstock 40 beats watching Glasto from the comfort of your sofa.
