The term 'Like Unkeyed Music' is a reference to ATONAL music, which is a type of music that does not conform to any key or tonal center. ATONAL music is composed of notes that are not related to each other in any particular way, and it often has an unpredictable and chaotic sound. This type of music was developed in the early 20th century by composers such as Arnold Schoenberg and Anton Webern, and it has been used in many different genres since then.