that it should remain art, and it's crucial that it should progress as art. ♪ >> the british invasion changed pretty much everything. >> it was not just a sound or a band or a phenomena. but it was the beginning of the most powerful decade in popular music. ♪ >> rock 'n' roll music was very important in the growth of the society. we were able to speak our minds. we did shake up the world. >> there's no desire in any of our heads to sort of take over the world. there is, however, a desire to get power in order to use it for good. ♪