Most of the cantatas Bach wrote during his tenure in
Weimar are to texts of Salamo Franck, the head of the mint at the Weimar
court. Franck is the best of all the poets that Bach set, and our cantata
today BWV 165 is one of his greatest works. The subject is the purification
of the human spirit by baptism, and Franck constructs a moving and poetic
set of images to discuss this difficult topic.
The opening soprano aria uses the image of bath water as the purifier
of the soul and as the inscriber in the book of life. Bach’s music is
both watery and visionary. The fugue for strings and soprano voice resembles
some of the ethereal slow fugues found in the Well-Tempered Clavier.
The religious ecstasy achieved at the words “and grants us the new life”
is breathtaking even for Bach.
The first bass recitative vividly characterizes both the guilt of the
sinner and the radiance of being clothed in the “white silk of Christ’s
innocence.” The alto aria is disciplined in its utterance. The slow
motor of the continuo acts like a prayer wheel, a sure and steady path
to salvation. The ecstasy returns in the marvelous accompanied recitative
again for bass. It should be noted that there are two separate snake
references. The first is the more common image of Satan. The second,
the “blood-red serpent image” refers to a common medieval portrayal
of Christ in Limbo as a snake on the cross. This was already an archaic
metaphor in Bach’s day but the church at Weimar had a well-known icon
with this image. The reference was thus clear to parishioners there.
The obbligato for all the violins in the tenor aria snakes along and
clearly has the both Satanic and the Christ-like function. A harmonization
of “Nun lasst uns Gott, dem Herren” completes the cantata.