Composed for the eighth Sunday after Trinity, which fell on June 18, 1723,
Bach's Cantata No. 136 "Erforsche mich, Gott, und erfahre mein Herz" (Inquire of me, God, and examine my heart) (BWV 136) sets an anonymous text based on Psalm 139:23 and concludes with a chorale by Johann Heermann from 1630. Although there are indications that at least some of the cantatas movements are based on pre-existing models, the earlier works have not yet been discovered. The cantata is scored for tenor, alto, and bass soloists with chorus, oboe, oboe d'amore, strings, and basso continuo, and clarion horn in the outer movements. "Erforsche mich, Gott, und erfahre mein Herz" starts in A major in its first movements, its second movement is in C sharp minor, its third in F sharp minor, and its fourth, fifth, and sixth movements in B minor. The first movement is a spacious chorale fugue with an independent orchestral ritornello. The second is a secco recitative for tenor soloist and continuo. The third is an aria in the form of a trio sonata for doleful alto soloist, obbligato oboe d'amore, and continuo. The fourth is secco recitative for bass soloist and continuo that becomes more dexterous at the close. The fifth is a 12/8 duet aria in the form of a trio sonata for virtuoso tenor and bass soloist, unison violins, and continuo. "Erforsche mich, Gott, und erfahre mein Herz" concludes with a chorale harmonization for chorus, descant first violins, and the remainder of orchestra colla parte.