God the Lord is Sun and Shield in G major, BWV 79

The text was written by an unknown poet, who did not refer to the prescribed readings for the day. Bach began the libretto for the feast with a quotation from Psalm 84 and included two hymn stanzas, the first from Martin Rinckart's "Nun danket alle Gott", associated with Reformation Day in Leipzig, as movement 3, and as the last movement the final stanza of Ludwig Helmbold's "Nun laßt uns Gott dem Herren". Bach composed a work of "festive magnificence", structured in six movements, with an aria following the opening chorus, a pair of recitative and duet following the first chorale. He scored the work for three vocal soloists, a four-part choir, and a Baroque instrumental ensemble of two horns, timpani, two transverse flutes (added for a later performance), two oboes, strings and continuo. He achieved a unity within the structure by using the horns not only in the opening but also as obbligato instruments in the two chorales, the first time even playing the same motifs.