Check out this interview snippet with the great Bill Evans from 1966 where he discusses improvisation and the sound of spontaneity in compositions. A lot to chew on both in a historical context and how it relates to present day music with the abundance of technology we have at our fingertips. It's amazing to think he was in the midst of a movement, a fresh art form (jazz) where musicians were not only creating spontaneously and being heard that way live, but it was getting passed on and actually heard that way because of the ability to record. As opposed to classical composers from the 17th century‚ as he mentions.