The Partita in D minor for solo violin (BWV 1004) by Johann Sebastian Bach was written during 1717–1723. The theory of professor Helga Thoene states that this partita, and especially its last movement Chaconne, was a tombeau written in memory of Bach's first wife (and 2nd cousin), Maria Barbara Bach who died in 1720. According to Maria Barbara’s second surviving son, Carl Philipp Emanuel, her death in 1720 came quickly and unexpectedly: Johann Sebastian was accompanying his employer, the Duke of Köthen, as the duke went to take the waters at the Carlsbad spa (the Duke brought his musicians along to provide him with entertainment). When he left, Maria Barbara was in normal health; when he returned two months later, he learned that she had died and been buried on 7 July, a week before his return. It is hard to imagine how this must have affected him. The cause of her death is unknown.