The Silent Instrument III
On the handling of appogiaturas. Louis requested no vibrato on the non-harmonic tone, but greater expression. He wanted us to know that this was not simply a gesture toward period-instrument polemics, but indicated by the music.
"Senza vibrato is not for the style but for the sigh. When I ask for senza vibrato, it is not that I want to take something away, but I want to add expression from the bow arm. Never make a general sound —the International sound—but always choose the sound you will make. Make it specific to the line."