early sonatas "for piano and accompanying violin," were
actually piano pieces; so much so that if the violinist failed
to appear, the listener would have only missed some supporting
passages that functioned as a doubling of the piano part.
With maturity - both personal and musical - Mozart created
sonatas where the violin took on increasing importance, with
more solo lines of its own, as you can hear in the movement
you may listen to here, the opening “Allegro con spirito” from
the G Major Sonata, K. 301.
Notes by Alan Grishman