A Dictionary of Music and Musicians/Improvisation
IMPROVISATION, an equivalent term for Extempore Playing or Extemporising. Moscheles has left a curious account of the way in which Mendelssohn and he used to amuse themselves by improvising à quatre mains, a feat already mentioned in respect to Beethoven and Wölffl under Extempore. 'We often,' says he (Life, i. 274), 'improvise together on his magnificent Erard, each of us trying to dart as quick as lightning on the suggestions contained in the other's harmonies and to make fresh ones upon them. Then, if I bring in a theme out of his music, he immediately cuts in with one out of mine; then I retort, and then he, and so on ad infinitum, like two people at blind man's buff running against each other.'
Nottebohm remarks in his 'Beethoveniana' (p. 54) that of all Beethoven's string quartets that in C♯ minor (op. 131) has most the character of an Improvisation, but at the same time he quotes alterations from the sketchbooks (15 of one passage only) which show that the work was the very reverse of an impromptu, and the result of more than ordinary labour and vacillation, thus corroborating the remark made in the article on Beethoven in this Dictionary (p. 174a) that the longer he worked at his phrases, the more apparently spontaneous did they become.[ G. ]