The written and spontaneous parts of the music contribute equally to the impact of Where will it take you?
Here’s Jason Yarde talking about the art of improvisation and how it relates to what he writes for his musicians. Improvisation is sometimes called ‘spontaneous composition’, and it can be hard to tell where one ends and the other begins.
The improvised notes from Jason's alto sax seem unrelated to it – there are a lot more of them, they don’t refer to the tune, they go off into squeals at the upper end of the instrument’s range. And yet somehow they belong with that melody, and don’t include clashing notes (dissonances) that don’t belong to the scale the tune is in.