It's all about dopamine squirts. When the brain has a lot of information to process at the same time, it secretes dopamine, making the combination of processes that are involved when playing the violin a pre-frontal cortex pleasure festival. There is the pleasure of getting the hands and fingers to work together, the pleasure of having good form and a good hand position, the pleasure of figuring out exactly where the fingers need to go to play a passage easily, the pleasure of being able to do a bow stroke, and then there is the pleasure of hearing something that actually sounds good. The "actually sounding good" part of the experience has everything to do with the developed mechanics of playing, and the real reward is that once the dopamine wears off the music is still there.
I have been spending most of my time this past week working on writing a piece of music, and the time I have spent with my violin has been rather superficial and Sevcik-less. After two days I started finding it difficult to play in tune, and I felt my newly-trained thumb try to slide back into its old position. Now that I'm finished with the piece, Mr. Sevcik has come back into my life, and I'm back in the violin saddle again. I feel much better. Hmm. Maybe I'll try a little Dounis now.