Significant achievements of J. S. Bach studies in the second half of the twentieth century were largely due to increased attention to Bach's handwriting and its changes during the life of the great composer. Its systematic study (using scientific methods, in particular, forensic graphology and medicine), according to sources, dates back to the late 50s of the 20th century and relates to the works by Georg von Dadelsen and Alfred Durr in the 70s in the works by Robert Lewis Marshall and to a large extent-in the late 80s and in the 90s-in the studies of Yoshitake Kobayashi. The main achievements in this field relate to:

1. Solving the issues of authorship of a number of Bach's works (and members of his family), as well as authorship of the works erroneously attributed to him. It was reflected in the latest BWV (1998) edited by A. Durr and Y. Kobayashi.

2. Establishment of the dating of the most problematic array of J. S. Bach's works relating to the late period of his activity (1736-1750).

3. Disclosure of the features and details of Bach's creative process, details of the process of publishing the compositions and his personal participation in it (Chr. Wolf, Y. Kobayashi, G. Butler).

4. Clarification of issues related to J. S. Bach's disease, its course and factors that led to the death of the great composer (D. Kranemann, R. Ludewig).

A comparison of features of handwriting in Bach's letters (31.07.1748 and 06.10.1748) shows that the period between the dates of their writing Bach suffered a minor stroke (TIA).

Further study of J. S. Bach's handwriting has a fruitful perspective. Thus, for the time being, methods of handwriting in the analysis of J. S. Bach's works, published (or prepared for publication) during his life, are not used for analysis of so-called original editions.

Since the method of printing used for the publication of his works retained the basic features of the handwriting of a person producing the engraving copy (Abklatschvorlage), it becomes possible to establish its performer. This opens up broad opportunities for establishing participation and role of J. S. Bach in shaping the general ideas of his writings, and for further development of this hitherto insufficiently explored sphere of his creative process.