Topics by Week
Cantus Firmus with
Some of Bach's most beloved works fall in this category. "Now Thank We All Our God" is the basis for his Cantata BWV 79 Gott, der Herr, ist Sonn' und Schild. While there are many sonorous settings of this chorale, Bach uses the very simple version which follows. Before examining the prelude, familiarize yourself with the following chorale setting upon which it is based.
Obbligato or Ritornello
Gott, der Herr, ist Sonn' und Schild means "God the Lord is Sun and Shield. The cantata was written for Reformation Sunday and its theme is thanksgiving. In the third movement the choir sings the above setting of Nun danket with obbligato brass. Obbligato means an "obligatory" part that cannot be omitted. In this case it refers to the brass fanfare accompanying Nun danket. In this version, the chorale is played by the organ.
Notice that in the cantata setting the chorale was stated homophonically--that is, in four parts with words being sung at the same time. This is the first time we have encountered this. In prior examples the melody was accompanied polyphonically--with free counterpoint in the other voices. Notice, too, that the brass obbligato plays throughout. It is for this reason that the chorale must be kept simple...so the two ideas will be distinct from each other. I like calling this type of cantus firmus treatment cookie in cream because the obbligato really adds something special to the chorale. Johann Sebastian's most famous piece, Jesu, Joy of Man's Desiring (from BWV 147) is another "cookie in cream."
Of course, some people don't like to dunk their cookies IN the cream...they would rather take a bite...then a sip...never mixing the two. In Bach's Singet dem Herrn (Motet BWV 225) there is a poignant section where Choir I sings a chorale in four-parts: "As a father is merciful to his little children, so is the Lord to us all." Between phrases Choir II interpolates: "Oh Lord, continue to care for us." In this setting the cookie (chorale of Choir I) never mixes with the cream (interpolations of Choir II). Ritornello is a musical idea that "returns" between the cracks of the main idea. If we think of the chorale melody as the longer idea, Bach's interpolations would be ritornelli. Unlike cantus firmus with obbligato, the new idea is not sounding continuously against the chorale melody, but only between phrases.