The five variations on “Von Himmel Hoch” are not variations in the usual musical sense. They are not five statements of the theme with ornamentation. They are five movements which all use canon to build up the music. During the last years of his life Bach composed several works which were based on canons. Several of his works from that period are canonic, including organ pieces from Parts III and IV of the Clavier-Übung, the Goldberg Variations for harpsichord, the Musical Offering and the Art of the Fugue.