Music that was, at first, composed with notes strictly and systematically organized, taking all twelve notes of Western music, and using each one, ad infinitum, in a chosen sequence; variation came via transformations of that "tone row". Meant as a death blow to tonality (founder Arnold Schönberg had already done "free atonality", sans system), it became widespread - with occasional liberties taken, and with some quasi-tonal works done as well - later spawning serial music.