There is so much great footage, it could have been done just the other week, because everyone looks exactly the same. Every festival today has some sort of debt to Woodstock in some way.

It does bring a freshness to a story that we've heard a million times.

Some optimism is required to allow for the possibility that the chaos of Woodstock offered a template for anything, but, if you inhale deeply, the film just about achieves this microcosmic ambition.

... For one golden summer at least, there really was a beautiful truce in America. A generation united under a freaky rendition of “The Star Spangled Banner” and got by with a little help from their friends.