I find it a real joy when I find two books that give me pleasure end up converging on a common theme. So it seems to be with David Schneider's books about the San Francisco Symphony, which rewarded me with that wonderful quote about good listening from Igor Stravinsky, and Ira Gitler's, Jazz Masters of the Forties. It turns out that Dizzy Gillespie felt just as strongly about good listening as Stravinsky did. He just had a different way of expressing himself. Here is Gillespie in his own words, extracted by Gitler from an interview conducted by Gene Lees:
I find nowadays that musicians are not as inquisitive as they used to be. You’ve got to be inquisitive. You’ve got to know why. If you respect a guy’s playing and he does something and you don’t know why, you say, ‘Why did you do it?’ What he does is easy to find, you can listen to the record. Why is what is important.
To invoke Stravinsky's approach, getting at the "what" is a matter of hearing; but it takes listening to get to the "why!" Adding my own spin to this observation, answering that "why" question, in turn, can involve appealing to matters of logic, grammar, and rhetoric, often in subtly interrelated combinations. Finally, by bringing Stravinsky and Gillespie into the same camp, it should be clear that good listening is equally relevant to composed and improvised music (although in different ways)!