Was the violin piece played by the character of Fargas in Polanski's movie The Ninth Gate (when the main character Corso meets him in his mansion) created for the movie or based on a real, pre-existing piece?
The piece is diegetic music, and one of the movie's themes is the devil, so I was thinking it could be some sort of musical reference, as Polanski often quotes other artworks in his movies. The music sounded also kind of familiar to me when I heard it the first time.
You can hear it playing in the soundtrack at 26m:15s :