Remember, this was the soundtrack to many a skip day from school, meaning it was always accompanied by a certain vibe, central to the era! Everything was Indian and sitar-y and 70's-laden.
Musically the album is a sort of concept with Revelation running loosely as a theme, then the double LP culminates with a long hugeantic medley that encapsulates the whole piece.
In between? Lots of period vocals, Vangelis' amazing synthesizers and keyboards, and all in all a really heavily hippyfied record from the time period where you could listen to this and really be transported. Check it out.