This definition of jazz by Ralph Ellison is the best one I've read:
"True jazz is an art of individual assertion within and against the group. Each true jazz moment (as distinct from the uninspired commercial performance) springs from a contest in which each artist challenges all the rest; each solo flight, or improvisation, represents (like the successive canvass of a painter) a definition of his identity: as individual, as member of the collectivity and as a link in the chain of tradition."
I came upon this brilliant definition in John Leland's book 'Hip: The History', and Leland further asserts that without both group cohesiveness and individual flights away from the center, a jazz combo will not fly.
I think this is sort of the way we work in advertising too. Its a team of planners, account guys, creatives making the ad performance fly for the client and customer audience. And I'm sure this is true for most other creative professions too. We all have our individual personality, thinking and viewpoints and each member's viewpoint kind of challenges the collective knowledge of the team and in between massive arguments and disagreements, sparks sort of fly and brilliant work comes out. Alas, as any great jazz number this is not an easy task to pull off and only few agencies get it right (if at all anybody gets it right!).