Spiritual Unity, recorded on July 10, 1964, is the album that made Albert Ayler and ESP-Disk' famous (or, in some people's eyes/ears, infamous). Mr. Ayler had already recorded in Europe and, in February '64, in New York, but this was the first album on which neither he nor his collaborators held back. It was also ESP's first jazz recording. Spiritual Unity presented a new improvisation paradigm: looser structure, less regard for standard pitch, and no obligation to present a regular beat. Ayler's sound was unprecedented, much rawer than any other jazz of the time. Sometimes it was expressed in squalls of untempered sound, sometimes in outbursts of poignant spontaneous melody. Meanwhile, under and around the leader's unfettered self-expressions, bassist Gary Peacock and drummer Sunny Murray reinvented the roles of their instruments. This is one of the cornerstones of avant-garde jazz and is truly essential.