The song "The First Time Ever I Saw Your Face" by Roberta Flack. Wow...What a classic.
It's my understanding that Clint Eastwood either heard the song (First Time...) or Roberta sing and wanted her to do something for a movie soundtrack. The result was "First Time..." which was used in the movie "Play Misty For Me" as a love song theme for Clint and Donna Mills.
Did the song predate the movie? I really can't say. Perhaps someone else can help here. It's my understanding, by the way, that clint is a big jazz lover ( i.e. Mingus, Charlie Parker) and is quite a musician himself. If memory serves me I think Clint did a movie about Charlie Parker or one of the jazz greats. Again, anyone know?