Sunday, 12 February 2012
In classical music, a crab canon is a canon in which one line of the melody is reversed in time and pitch from the other. A large scale musical palindrome covering more than one movement is called "chiasic" referring to the cross shaped Greek letter "χ" (pronounced /ˈkaɪ/.) This is usually a form of reference to the crucifixion for example, the crucifixus section of the Bach B-minor Mass. The purpose of such palindromic balancing is to focus the listener on the central movement much like one would focus on the center of the cross in the crucifixion. Other examples are found in Bach's Cantata BWV 4, "Christ lag in Todesbanden", Handel's Messiah and the Fauré Requiem.