Thanks for the info everyone. What led me to ask the question was watching this and this and this and thinking about how absolutely awesome it would be to be a rockstar, to share your music with a dancing crowd, to connect to other people so physically through your art, to be a part of something like Woodstock, to be THE BEATLES, to be innovators at that level, to change everything.
And I thought it would have been cool had The Beatles been at Woodstock and there to see Santana get famous, to see Crosby, Stills, & Nash play Suite: Judy Blue Eyes before they had it fully worked out live, to see Arlo Guthrie, just a kid with a guitar, get up there and do his thing in front of all those people.
I think it would have been so much fun for The Beatles to see that, to experience it with those other musicians, because The Beatles participated in creating it, because, without The Beatles, there might never have been a Woodstock. They were an historical hinge. The world was different, in part, because of them. And I hope they knew that and felt good about it, because I think they made the world better, and people that make the world better should get to experience and enjoy and appreciate those improvements.