Thomas Braatz wrote (September 9, 2001):
BWV 164 - Comments on the Mvts (Musical Form and Content):
Dürr wonders why, with a reasonably rich instrumentation, there is no concertato style, but rather only instruments that play solo or in unison. The mvt. seems to have a bipartite form: A, B, A', B' but the more you examine it, the more complicated this mvt. becomes, In reality A (measures 31-42) = A' (75-86) and B (64-72) = B' (92-101.) After the Ritornello (1-8) in which the 1st and 2nd violins engage in a "Canone all Unisuono," the tenor voice (9-12) picks up the same canon, now an octave lower, "Canone all' Ottava," in what is called a "Vokaleinbau" ("a vocal in-building.") This term, used by Dürr to describe a situation where the opening instrumental ritornello, contrary to its usual use to provide an interesting, sometimes vaguely related musical material, now presents the thematic material that will be repeated by the voice, which may, but does not, as in this mvt., add any new material to it. "Vokaleinbau" is not to be confused with another Bach aria feature where Bach has the singer begin the aria with a unique theme/phrase, which, after a short pause (short musical interlude) is once again repeated before proceeding into the aria - a rhetorical device applied to music. Here, at the beginning of this mvt., we have both the 'Vokaleinbau" and the repetition of the initial vocal phrase. Throughout the mvt. Bach keeps moving the canon up and down and introduces new motifs: a fifth higher, a third higher, a third lower, a fourth higher, etc. This is truly a masterpiece of musical form!
Mvt. 2 (Recitative):
The arioso section has led some to think that this is a quote from a chorale. Nothing has been substantiated in this regard.
Mvt. 3 (Aria):
This mvt. has an extended binary form: A (1-20), B (21-30) , B' (31-45)
Mvt. 4 (Recitative):
Mvt. 5 (Duet for Soprano and Bass):
Immediately after the announcement of the theme in the upper instrumental line, listen for the inversion of the theme in the bc. This mvt. is in essence a quartet: 1) the upper instruments playing unison 2) soprano voice 3) bass voice 4) bc.
There are 4 sections: A (1-42), B (43-69), C (70-100) , A' (101-154) Section A contains the "Canone all' Ottava," while B and C have a "Canone alla Quarta." Section A' contains the Vokaleinbau with an additional final instrumental ritornello. Along with all these canon statements, Bach also includes an equal number of inversions of the theme. Schweitzer and Dürr see the antithetical motions of the hands and interrelations between man's merciful attitude toward fellow man and God's mercy upon mankind reflected in Bach's inversions of the main canonic theme.
Mvt. 6 (Chorale):
Dürr questions whether a choir was really used at the 1st performance, and thinks that the chorale was most likely sung only by the four soloists.