You first have to have the idea (purpose) of the music that you are composing. You can not discover music with a mind focused on technical skills.

Considering Bach a “Klavierritter” [“a knight of the keyboard” – a pejorative term for those composers who sat at the keyboard, tried out each next chord or musical figure before committing it to paper which was on the music stand above the keyboard”] is certainly going much too far with the comments I had inserted. The compositional process in Bach’s case was more likely one of an improvisation to which he might return a few times on different occasions until it began to take a shape that he could live with. Then in his attempt to put these ideas on paper (his first copy or writing down on paper) without recourse to any keyboard instrument, other possibilities that he may have been hearing in his head (the instrumentation, the detailed connections between the text and music, etc.) would present themselves. Even in his truly original compositions (‘truly original’ here means that he is not copying from another work by him which he is adapting and revising, for instance, a secular to sacred cantata) where his handwriting indicates that he is working very fast (all the dots and tittles are not lined up accurately as they usually would be in a ‘clean’ copy which is, in essence, of an already existing composition,) Bach only infrequently finds it necessary to correct ‘false starts’ or to ‘try out a new form of the melody line in some vacant margin. This implies that he basically had the composition fairy well in mind before committing it to paper.

The situation related about the partitas is rather unique in that he was trying to make certain that certain passages were truly playable. He would ‘practice’ such passages and possibly make some slight revisions in the already existing score. He did not, in any case, compose the partitas primarily from playing them or short portions of them, and then writing down only in bits and pieces whatever he just played on the keyboard.

Bach scorned those he called the “Knights of the Keyboard,” who composed only on the keyboard (harpsichord, in his day) without any understanding of harmony that comes from the study of vocal music and counterpoint.

You first have to have the idea (purpose) of the music that you are composing. You can not discover music with a mind focused on technical skills.

I will try to find these quotes that I referred to earlier. I had already spent an hour looking for them the other day and could not find them. Now it seems it may be worth another try. If and when I find them, I will immediately share them with the list.

I believe that another type of compositional process may also have taken place: the unfolding of a germinal idea or concept (the antithesis kernel, for instance) may have presented itself directly to his mind with no need for any keyboard at any point along the way. This might appear as only 1, 2, or 3 measures of choir and orchestral parts condensed into only a few staffs. If I were to choose a ‘likely suspect’ in the 1st mvt. of BWV 3, it would be the final ‘overlapping’ where the choir ends and the ritornello has already begun. Since such a kernel would, unlike a single melodic line that Bach might occasionally place in a margin or an unused part of the music paper that he had prepared, take up more space and would be written on a piece of scratch paper that would be destined for destruction or use elsewhere; hence we have no evidence of this, but I think the possibility might nevertheless exist. From such a kernel the rest of the mvt. would begin to unfold more easily because the kernel contains the ultimate confluence of all the materials needed in the mvt.: all the instruments and voices are involved simultaneously at the highpoint of the cantata mvt. The image that comes to my mind here is that this is the point ‘where the snake bites its own tail’ – it is the ending but also the beginning at the same time.