This song was written on the plane to Woodstock, and was played for the very first time hours later. It actually punctuated what the freedom movement was all about with the exposure of materialism, greed, wars and corruption and the need to get back to the earth.
https://youtu.be/lSYFJB7o9ZQ

To this day I cannot listen to this song without tears of emotion welling up. In the past few days I have completed a new book called "Attack from the Future" and the ending paragraph details something very similar to this song.
Here is an excerpt from the book:
"Do you think the people on earth can turn things around Mike?" Jon asked, as Mike was piloting the space ship out of the atmosphere and into deep space.
"I don't know." Mike answered. "It is up to them now. It's either sink or swim. Americans have to realize there are dangerous predators out there, and they're going to have to stop them or be destroyed by complacency. There is no such thing as coexistence with a parasite."