“Prelude” from the Partita for solo violin, BWV 1006

Influenced by the Italian models of solo and trio sonatas that were circulating widely in Europe, Bach first ventured beyond the keyboard with two sets of works for string instruments – the six Sonatas and Partitas (three of each in alternating order) for solo violin, and later the six Suites for solo violoncello. These works date from the Köthen period, but it’s very possible that their composition could have been a process of several years started in Weimar.

For the Sonatas, Bach drew straight from Corelli’s typical structure of slow-fast-slow-fast movements, using a Fugue as the second movement. The Partitas are collections of dances, but they don’t follow a consistent pattern. Partita 3 is the only one that starts with a Prelude, which Bach reused for Cantatas BWV 120a and later BWV 29, turning it into Sinfonias by giving the solo violin line to the organ and adding full orchestral accompaniment.

“Cantabile” from the Sonata for violin and harpsichord BWV 1019a

Like many other collections, these Sonatas are a set of six. They date from around 1725, i.e. Bach’s early Leipzig years, and there are indications that Bach continued to work on them in the late 1740’s, a sign of the value that he saw in them. The slow movements in particular were advanced for their time in the 1720’s, with their elaborate and ornate melodies. These pieces are formally trios, since the harpsichord takes a partnership role to the violin, not just accompanying it as a bass line, but also carrying a concertante part with the right hand.

Bach used this Cantabile as the foundation for the soprano aria in BWV 120a first, and eventually in BWV 120. In the aria, the soprano line is essentially the melody that had been given to the right hand of the harpsichord.