"As usual he submitted to the interminable entreaties and finally was dragged almost by force to the pianoforte by the ladies. Angrily he tears the second violin part of one of the Pleyel quartets from the music-stand where it still lay open, throws it upon the rack of the pianoforte, and begins to improvise. We had never heard him extemporize more brilliantly, with more originality or more grandly than on that evening. But throughout the entire improvisation there ran in the middle voices, like a thread, or cantus firmus, the insignificant notes, wholly insignificant in themselves, which he found on the page of the quartet, which by chance lay open on the music stand; on them he built up the most daring melodies and harmonies, in the most brilliant concert style. Old Pleyel could only give expression to his amazement by kissing his hands. After such improvisations Beethoven was wont to break out into a loud and satisfied laugh."