Ein Herz, das seinen Jesum lebend weiß (A heart that knows its Jesus is living), BWV 134, is a church cantata for Easter by Johann Sebastian Bach. Bach composed the cantata for the third day of Easter in Leipzig and first performed it on 11 April 1724. He based it on his congratulatory cantata Die Zeit, die Tag und Jahre macht, BWV 134a, first performed in Köthen on 1 January 1719.
The prescribed readings for the feast day were from the Acts of the Apostles, the sermon of Paul in Antioch (Acts 13:26–33), and from the Gospel of Luke, the appearance of Jesus to the Apostles in Jerusalem (Luke 24:36–47). The unknown poet adapted the dialogues of the secular work of two allegorical figures, Time and Divine Providence, originally written by Christian Friedrich Hunold, one of the notable novelists of his time. In this cantata the poet kept the order of the movements, dropping movements 5 and 6 of the early work. He kept the final chorus as a conclusion, unlike Erfreut euch, ihr Herzen, where it had been moved to the opening and replaced by a chorale. Bach simply wrote the new text below the former text in his score.
Bach composed three new recitatives for a second version and first performed it on 27 March 1731. Bach revised the whole cantata, writing a new score with detailed improvements, possibly first performed on 12 April 1735.
The cantata in six movements is scored for alto and tenor soloists, a four-part choir, two oboes, two violins, viola, and basso continuo.
