(down bow and up bow), in every degree of tone, fortissimo, pianissimo, crescendo, diminuendo, sforzando, morendo—all this belongs to the natural realm of the string quartet.
The fact that these instruments are capable of playing double notes and full chords across three and four strings—to say nothing of sub-division of parts—renders them not only melodic but also harmonic in character.[7]
From the point of view of activity and flexibility the violin takes pride of place among stringed instruments, then, in order, come the viola, 'cello and double bass. In practice the notes of extreme limit in the string quartet should be fixed as follows:
for violins:
, for violas:
,
for 'cellos: