Classical music in films

Classical music is used in films in a diegetic way and a non diegetic way. 

Good examples of the use of classical musical diegetically are: 

- Children of a Lesser God  (1987): this is a scene with the teacher, played by William Hurt, and his deaf student and girlfriend, played by Marlee Matlin. The teacher tries to describe the beauty of the second movement of Bach's Concerto for Two Violins to his pupil by miming (using just his hands and body), because she can't hear. 

malick7272 Bach Double Violin Concerto Licencia YouTube

- The Shawshank Redemption (1994): a prisoner (acted by Tim Robbins) plays a record of Mozart's opera The Marriage of Figaro on the loudspeaker for the others to hear all over the jail. Actor Morgan Freeman is one of them and he is the narrator of the film. He tells us that when they listened to the beautiful opera aria, "for the briefest of moments, every last man at Shawshank felt free".

qlazer Mozart aria The Shawshank Redemption Licencia YouTube 

- The Ladykillers (1955): in this classic British black comedy, a gang of thieves hide in a house and pretend to be musicians rehearsing the Minuet from Boccherini's String Quintet in E Major upstairs in their room so that their elderly landlady won't get suspicious, but they are really playing a record! It's funny because they are obviously not musicians: they have no idea at all about how to even hold their instruments!

Claude LE-QUANG The Ladykillers Licencia YouTube

And some famous examples of classical music used non diegetically are: 

- Manhattan (1979): director Woody Allen opens this film to Rhapsody in Blue by George Gershwin. In this way, Allen's love for New York is mirrored by his love for the music of this American composer, and he creates the perfect union between music and image.

Gianluca Rigamonti Woody Allen and Gershwin Licencia YouTube

- 2001: A Space Odyssey (1968). Director Stanley Kubrick chooses to use the famous introduction to Also Sprach Zarathrusta (1896), by Richard Strauss, to accompany the images of a space craft travelling through the universe. He had commissioned a score from a well-known composer for films (Alex North, who actually wrote it!) before deciding to use classical music. I don't know what North's score was like, but the use of the Strauss theme is very, very effective!

HD Film Tributes A Space Odyssey Licencia YouTube

- Apocalypse Now (1979): We have already mentioned this film for its use of diegetic music. It also uses non diegetic music with great force. Director Francis Ford Coppola plays the Ride of the Walkyries from the opera by Richard Wagner to create a terrifying atmosphere while we witness war scenes of horrific destruction. 

Phil B Wagner and Apocalypse Now Licencia YouTube