J. S. Bach’s tenure as Capellmeister in Cöthen, with its focus on secular music, afforded an opportunity to explore the violin and cello as solo instruments. While his Sonatas and Partitas for Solo Violin represent the pinnacle of an established German tradition, the Cello Suites are among the earliest music composed for unaccompanied cello and may have been inspired partly by unaccompanied music for viola da gamba (pièces de viole). Bach’s Violin Solos and Cello Suites are both “opus collections”—sets of (usually six) pieces exemplifying his mastery of a particular genre or instrument. An obituary coauthored by Carp Philipp Emanuel Bach and Johann Friedrich Agricola illustrates the special importance the composer attached to these pieces. While Bach was best known during his lifetime as an organist, he had intimate knowledge and full mastery of the violin. There is no record of Bach playing cello, but his composition of virtuoso suites that draw a maximum musical effect from such minimal instrumental resources suggest an intimate knowledge of that instrument. Moreover, during Bach’s lifetime, an instrument called “viola da spalla”—considered a type of cello but played similarly to the violin—could have enabled a violinist to play the Cello Suites.