"Abaddon's Bolero" is one of the tracks gracing ELP's "Trilogy" album and probably one of Emerson's best tracks. The structure and the title of this track have a patent reference to Ravel's famous composition because of its crescendo arrangement, while, of course, the theme is an original one. Keith's keyboards provide all the variations and the effects, and they surely are a treat, but I wouldn't forget the rythmic structure supporting Emerson's efforts.
That's what I call a crescendo!
Never boring, never predictable, "Abaddon's Bolero" change its unique theme in a profusion of moods, colours and impressions, so that the intellectual pattern of the track goes on perfectly well with its emotional power. A clever creation, a modern classic, a monument to progressive rock, IMHO.