J. S. Bach was not only teaching his students about musical ideas, but also tried to give them ideas about the singing style on performing and composition. He was really giving importance on singing; he thought that singing is the basic structure of music. An instrumentalist must think which techniques would be revealing the best melody or harmony. It is hard to reveal with playing an instrument, singing is more clear and distinctive.
In education, rhetoric thought is a need when studying, because it is conducive to understand both “grammatical and expressive” usage. In my opinion, rhetorical teaching basically gives to performers more ideas about how a performer can transfer the necessary thoughts in the composition (with his instrument or his voice) to listeners. In brief, it is useful to study and understand “figuration and techniques, basic skeleton of the piece, adding details individually.”
In Bach’s works, it is very significant not to lose the connection between the performance, composition and musical ideas. The performers should have an awareness of the ideas in the composition which came through to the performance. In sources of Bach’s, instrumental parts have more articulation parts than the vocal ones. In my opinion, he did this because he thought that it is necessary to mark every idea which he wanted to be performing, not because he did not rely on the performers and his students who can transfer these details.
Bach drew the bow in his works in such a way that; when performers play it, “a neutral articulation occurred between every stroke.” The usage of the bow by performers is likely to breathe for a singer. But the articulation that you made is much more than a singer must breathe – if you playing an instrument. It creates a “regular mandatory articulation”. Playing instrument and singing are related to each other because in each of them, you display a work that reflects ideas about the composition, and the ideas of the composer must be represented correctly. I think, doing articulation with the bow technique is harder than do it with vocal techniques because you need to hold the bow correctly for balancing the sound that comes from your instrument and should “press the bow lightly but steadily in the strings”.