Music included in this episode:
Vassily Kalinnikov - Symphony No. 1 in G Minor - II. Andante comodamente (1895)
The Beatles - “In My Life” (1965)
Willie Nelson - "I'd Have To Be Crazy" (1976)
Lauryn Hill - "Can't Take My Eyes Off of You" (1998)
(Update: a commenter pointed out that my analysis here accurately describes the original Frankie Valli version, but Lauryn Hill uses the minor iv chord in her intro.)
Read more and see transcriptions here.