That is an amazing song. It’s one of those that’ll make you sit in the driveway till it’s over.
http://www.youtube.com/watch?v=-x5yb98aGQE&feature=related
In addition to the enthralling, elegant artistry of "Shine on You Crazy Diamond," the pathos of it is, I think, a startlingly realistic summation of... themselves, and of the 'hippy movement,' and rock culture, while still trying to cling to the lure of it all.
(BTW, I agree with those who say that the tragic drop-out of Sid Barrett was about the "best thing that could happen" to Pink Floyd. If he'd not blown out his mind, I think he'd continue to have narcissistically taken the limelight with his funky court minstrel songs and I'm guessing the rest would have gotten frustrated and the band would have split like most do, after another year or three of success.)