One can only regret that Beethoven left only four piano quartets, as these four works rank among the most popular of this genre. Three of them, the Quartets WoO 36, had been penned in Bonn, which makes them one of the master's most successful juvenilia of all. Yet even if they exhale Mozart's spirit, they are already and unmistakably typical Beethoven. Further evidence of his regard for the pieces can be found in his re-use of the third quartet's slow movement in his first Piano Sonata op. 2 no. 1. The fourth quartet represents another version of the Wind Quintet op. 16.