Eine kleine Nachtmusik
Eine kleine Nachtmusik was a piece of classical music written by Earth composer Wolfgang Amadeus Mozart in the late 18th century. 

A crewmember of the  fantasized playing the first movement ("Allegro") of Eine kleine Nachtmusik on the violin, together with three other musicians in period clothing, when the starship was located in a part of the universe in 2364, where thoughts became reality. ()

A string quartet consisting of Data (playing the violin), Miles O'Brien (playing the cello), and two more crewmembers of the Enterprise-D (playing the violin and viola) performed the first movement of Eine kleine Nachtmusik in 2366. Captain Jean-Luc Picard later listened to an audio recording of the second movement ("Andante") that Doctor Beverly Crusher had made as he wasn't able to attend the concert. ()

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de:Eine kleine Nachtmusik
fr:Une petite musique de nuit

Eine kleine Nachtmusik