"I find that, aside from the personal illustration absolutely necessary
when teaching, that an appeal to the pupil's imagination usually bears
fruit. In developing tone-quality, let us say, I tell the pupil his
phrases should have a golden, mellow color, the tonal equivalent of the
hues of the sunrise. I vary my pictures according to the circumstances
and the pupil, in most cases, reacts to them. In fast bowings, for
instance, I make three color distinctions or rather sound distinctions.
There is the 'color of rain,' when a fast bow is pushed gently over the
strings, while not allowed to jump; the 'color of snowflakes' produced
when the hairs of the bow always touch the strings, and the wood dances;
and 'the color of hail' (which seldom occurs in the classics), when in
the real characteristic _spiccato_ the whole bow leaves the string."