The monogram that appears on this site and on the Bach Parley programs is based on J.S. Bach's personal seal. The design for the seal was formed from his three initials (J, S, and B), engraved in a flowing calligraphic style and overlaid with their mirror image.
Bach continued to play with ways to combine his three initials, and in five extant books and manuscripts he formed a monogram by graphically combining the first letters of Bach with J and S.
Charles E. Brewer