80, with the corresponding number in BWV 80a shown in brackets. The scoring and keys are given for the late Leipzig version. The keys and time signatures are taken from Dürr, using the symbol for common time (4/4). The instruments are shown separately for winds and strings, while the basso continuo, playing throughout, is not shown. In the first movement, there are two basso continuo lines – the first played by a violoncello and cembalo, and the second by a violone and organ. Movements Chorale fantasia The cantata opens with a chorale fantasia "with contrapuntal devices of awe-inspiring complexity". The movement in D major and common time elaborates on the first stanza of the hymn "" ("A Mighty Fortress Is Our God"). It adopts a motet technique of having the instrumental and vocal lines follow each other closely. The Bach scholar Klaus Hofmann noted that the style relates to the "vocal polyphony of the sixteenth century", when the Luther hymn was written. Structurally, the movement repeats the first two phrases, adds four new shorter phrases, then concludes with another iteration of the second phrase, all performed on oboe. All four voices "discuss each phrase imitatively as a prelude to its instrumental entry", using fugal devices. The chorale also makes use of the cantus firmus, which is exclusively played in the basso continuo and oboe lines (in the movement's original form). Aria e chorale The second movement combines an aria and chorale: the bass sings free poetry, "" (Everything that is born of God), while the oboe and soprano perform the second stanza of the hymn, "" (Nothing can be done through our strength), in an embellished version of the chorale melody, particularly in the oboe line. Like the first movement, the duet is in D major and common time. The musicologist Richard D. P. Jones interpreted the theme of the ritornello, played in unison by the strings, as a motto of victory, corresponding to the two mentions of victory in the text. In the Weimar version, the instrumental quotation of the tune of the same hymn used as the closing chorale provided a structural unity to the cantata. Jones compared the "extremely florid" rendition of the tune, given to the soprano in the Leipzig version, to the similar approach in the chorale played by the oboe d'amore in movement 5 of the Weimar cantata for Pentecost, Erschallet, ihr Lieder, BWV