The rarest of all Don Ellis sessions, Essence matches the trumpeter with pianist Paul Bley, bassist Gary Peacock, and either Nick Martinis or Gene Stone on drums. Ellis, who sought during this period to transfer ideas and concepts from modern classical music into adventurous jazz, often experimented with time, tempos and the use of space while still swinging. His renditions of Billy Strayhorn's "Johnny Come Lately," "Angel Eyes" and "Lover" are quite fresh, he contributes four interesting originals and introduces Carla Bley's "Wrong Key Donkey" (here simply called "Donkey"). This is thought-provoking music that was certainly way overdue to be reissued.