Vince Guaraldi's classic "A Charlie Brown Christmas" music

How did this song ever become a classic? It's kind of a melancholy waltz, and the chords are really complicated. It's not "Jingle Bells" … it's jazz!

It's called "Christmas Time Is Here":

It's story begins in 1965, when CBS asked producer Lee Mendelson if he could put together a Christmas special in six months.