It's been a while.
I've mostly been listening to some old vinyl I bought for pretty cheap but never really knew too much about. This isn't one of them (I'd listened to the song all the way through a few times before, and I'd definitely listened to Jethro Tull) - but I still found it on vinyl for a $4.99. Not bad, eh?
For a 43:46 minute long song, this captivates extremely well. There is not one part of this entire song I dislike. The entire piece keeps throbbing and pulsing for the whole album - the song itself feels alive. I especially love how it has variations to keep you interested, but it keeps returning to one main theme - no change in the song is ever random or unnecessary. It is still one whole song as opposed to a compilation of different ones played in a row (as some unmentioned longer songs sometimes feel).
Give it a listen, PLEASE. It's really a beautiful piece as a whole (Although it's not possible to listen to it all the way through on vinyl. The record has to be flipped over at some point. I still recommend trying to hear the whole thing all the way through, if you can possibly sit still for that long).
(Is this an album or a song review?)