From Degrees to Feel: First Principles of Embodied Rotation
To have good control of the instrument requires precise control of very fine degrees of rotation. Just how fine? Consider this: for the left hand there are all the fingerboard positions, plus the different angles of different strings, not to mention various angles of hand frames for different configurations of intervals (e.g., major 3rds vs. minor 3rds).
With the bow arm, there is not only the different positions of the strings, but also various parts of the bow along its length. In order for them to work together, the whole body needs to work together in order to rotate to very precise degrees. And depending on the individual body, those degrees will shift according to a person's own alignment patterns.
Beyond basic descriptions like pointing the scroll at a 45-degree angle or "more to the left/right," there is much finer precision. For instance, in any given moment, the chest is rotated a certain amount to the left, the lower spine counters in the opposite direction, and the lower body generates torsion in varying directions—with the ankle, foot, lower leg, and upper leg all participating in the whole chain.
However, we can't be thinking about this in mathematical terms when performing—well, not even when practicing! With the hundreds of joints and all the complexity of the human body, we need to translate this into a feel-sense in our playing. So, to pinpoint how exactly far left or right each individual's scroll should point at any given moment (because that's not static), we factor all these other things in. We start from a first principles understanding of what the body needs to do for that specific motion or posture, then examine the most natural way for our body to execute that motion. Along the way we might discover that our body has inherent difficulties with certain rotations in specific directions even without the instrument, so we need to try to correct that. And finally we expand and refine the range we need to arrive at the most natural way each of us can accomplish that action successfully.
And swinging is one way that can naturally help us determine many of these trajectories that the different parts of our bodies need to go. My belief is that many of the difficulties of violin playing come from its asymmetrical nature. If the trunk isn't organized well enough, the limbs eventually hit a wall in natural motion—and that's where a lot of the root of technical difficulties lie. But it's almost impossible to analyze mathematically what needs to happen in the whole body. I feel that swinging can provide a lot of clues to this puzzle and has the potential to help naturally solve many of them. I'll share more about that.