All three of today’s works have a special relationship with semitones. For example, the Haydn opens with one that metamorphoses into its main theme; the Janáček opens with a harsh F#-G clash which sets the tone of this emotionally-charged piece; the Beethoven, famously, is built around the opening two embedded pairs of semitones. You can probably spot more examples.
Josef Haydn (1732-1809) String Quartet Op. 74 No.1 in C (1793)
Menuet & Trio
Haydn’s six ‘Apponyi’ quartets (Op 71 and 74) were written in 1792 & 1793 between his two extended visits to London. Prince Nicholas Esterházy, Haydn’s patron to whom he was devoted, had More