Prelude: Reflections on Music, Art and Three (yes, as in the number 3): How different are my Escher-like stairs from yesterday than once of today? J. S. Bach's canon per tonus from his Musical Offering is a very famous example of an endlessly rising melody. The melody rises two halftones each time the canon is repeated ("As the keys ascend so may the glory of the king also ascend" - this should illustrate the rising glory of Frederick the Great to whom the Musical Offering was dedicated).