Composed 1723; 30 minutes

Bach organized his 15 three-part Sinfonias like the 48 Preludes and Fugues in a symmetrical, ascending manner, beginning with C major. He gave these keyboard Sinfonias an earlier title of “Fantasias” when he entered them in an instruction book (Clavierbüchlein) he made for his eldest son, Wilhelm Friedemann. He also titled the 15 two-part Inventions “Praeambula” in the same book. His aim in writing both collections of “inventions” was clearly didactic. The autograph copy he made, dated Cöthen 1723, shortly before he moved to Leipzig, now refers to the “Fantasias” as “Sinfonias.” All these works each derive from a single idea or musical thought from which the “Invention” is then created. “I felt that they worked in this program because they’re so short and so concentrated in what they have to say,” Simone Dinnerstein says about the Sinfonias, adding that “something about them is abstract and modern.”

The title page of the autograph copy includes the following description of Bach’s aim: 

Sincere instruction, in which lovers of the keyboard, especially those who are keen to learn, are shown a clear method, not only 1) of learning to play in two parts, but also, after further progress, 2) of dealing well and correctly with three obbligato parts. At the same time, they are shown both how to come by good ideas, and also how to develop them well. Above all, however, they are shown how to arrive at a cantabile style of playing, while also acquiring a strong foretaste of composition. 

So, in Bach’s progressive plan for instructing his sons and his other pupils, the two-part Inventions lead the aspiring composer and keyboard player to the three-part Sinfonias and from there to the four-part fugues of the ’48.’