David Grohl thoughts

I was watching Foo Fighters most recent story tellers episode and David Grohl was talking about the song Hero and said it was written during rehearsals.  He just filled in some words to fit the melody and they ended up sticking.  That has happened to me before.  Sometimes, I have a set of words written down then sit down and write a melody, but more often I start plucking away at a song and use filler words or even just syllables that seems to fit the cadence and character of the song.  Later, when I go to write 'official words' down, sometimes the words that I was mumbling seems to stick.   A new song the band is playing called Proclaim is a good example of that.