I've been studying harmony and composition with a guy (a clarinetist/saxophonist with a heavy classical/jazz background) and, upon finding my technique somewhat, er, un-awesome, he sent me into some position exercises... He got me the Bach Sonatas for violin and the Carl Flesch Scale System... Man, I had no idea! Hand position has been a major revelation to me, and I've only scratched the surface! I can already see how pieces which were impossible are now just challenging... Exciting stuff!
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