The siciliana, as a genre in compound time, along with the allemanda in simple time, seem to have been written strictly as musical interludes (or preludes). It is believed that in Bach's time, these pieces were not actually danced in ballets or in courts; there are no surviving choreographies or any kinds of written descriptions of them as actual dances. Nevertheless, with its lilting rhythm, this Siciliana is very much like a dance and, like all the third movements in the sonatas, it is characterized by its songlike quality, and is in a closely related key, here B-flat.

While the Baroque sonata da chiesa typically had four contrasting movements, alternating slow-fast-slow-fast (Corelli’s sonatas sometimes had as many as eight movements), one might think of Bach’s violin sonatas as being a prelude-and-fugue, followed by a song-and-dance.

Indeed, in each of these sonatas, the third movement is particularly beautiful and very lyrical. This movement is where we hear most prominently how Bach’s sonatas are derived first and foremost from vocal music, and, in this regard, the Siciliana in B Flat is a very touching song for three or four voices.

There are two tutorial videos, linked on the right. They explore Bach’s use of choral techniques in the Siciliana, and also discuss the architecture of this deceptively simple masterwork. Part one deals only with the section in which Bach establishes his key and then leaves it; part two discusses the return home and then the denouement that follows.

The concluding section of this Siciliana is very different from anything else found in the Sonatas and Partitas. We came across some questions there, which we likely would not have run into had we only been playing Bach’s notes. While arranging this section, and wondering if we would add any basses or inner voices, we saw that there were phrases in which the harmonies seemed so ambiguous, we could only assume that we were missing something. For seven years we kept revisiting those measures, and finally were led to a most interesting answer by Robert Gjerdingen, a brilliant musician and theorist who is very knowledgeable about the music of the Style-Galant composers. All this is discussed in the video, part-two.

There is also an article linked on the right that discusses Bach’s use of vocal music in the sonata da chiesa.