Bach structured the work in five movements, a sinfonia, a recitative, a recitative with chorale, an aria and a closing chorale. He scored it for three vocal soloists, a four-part choir only in the chorale, and a Baroque instrumental ensemble which is unusual in having violas but no violins. The instruments originally specified were four violas, cello, bassoon and basso continuo. When he performed the work again as "Thomaskantor" in Leipzig, he added two recorders to double viola I and II an octave higher, thus creating a lighter sound overall.