He said that a bass player should
lift everything up and make it deeper and more full-sounding…in order to inspire the other musicians to play better than they’ve ever played before.I think the whole interview is worth reading (ok--the whole book). I resonated with his comment because it encapsulates what I try to do as a church musician and accompanist. Collaboration is fun. I'd much rather do that than do a lot of solo performance, even though it takes more preparation to produce an effective ensemble. Even as a composer--although I'm obviously responding to some sort of creative urge over which I have little control (well, I have some control over what I write, but not that I write)--I follow the principle of inspiring other musicians and the audience to become better. Occasionally I succeed.
As I've gotten older I've given more thought about what I do. I try not to do so while I'm playing, since that distracts me from actually making music. While a bass physically can make things "deeper and more full-sounding" simply because it plays in a lower register than most instruments, I think Charlie Haden is referring to more than the mere notes. There's an element of musicianship that permeates the music; without the musicianship (which operates in multiple dimensions: time, timbre, vertical, horizontal, sound, silence) there's just noise.
His interview was thought-provoking, as were many others in the book. It makes me think of a book by, if I'm remembering correctly, Johnny Cash's daughter. 'Scuse me. It's around here somewhere...