We know more about Emanuel Bach's training and early compositions than about any other son or pupil of Sebastian. According to NV, ten keyboard sonatas and sonatinas, a suite, and two concertos, as well as seven “trios,” survive from his Leipzig years. In addition to a number of further compositions not listed in NV, we also have Emanuel's testimony about how his father taught performance and composition, not to mention school records and other documents from Emanuel's early years.

Yet these traces are of limited use for understanding how Bach learned his craft and found his distinctive musical voice. All the music acknowledged in NV as products of his Leipzig years was reworked during the following decade at Berlin, and it is unclear how much of it survives in its original form. His authorship of the pieces not listed in NV is uncertain, and the information that he provided late in life about his father's teaching methods could have been idealized or otherwise slanted—nor did he explicitly indicate that he was describing his own training. As for his personal or psychological development, we know little beyond the bare records of his attendance at the Saint Thomas school in Leipzig, following the family's arrival in spring 1723, and at the Leipzig university from fall 1731.