I just watched a doco about this Album,this song was written for a member of the band,who dropped some acid,and never came back.
I dont know if anyone knows how it feels,I once dropped some with a guy,and he was just gone,like his mind was erased,so this song realy hit home,well I always dug it,but hearing that,made it much more personal.
https://www.youtube.com/watch?v=cWGE9Gi0bB0