“In all its roles and appearances, improvisation can be considered as the celebration of the moment. And, in this the nature of improvisation exactly resembles the nature of music. Essentially, music is fleeting; its reality is its moment of performance. There might be documents that relate to that moment – score, recording, echo, memory – but only to anticipate it or recall it.
Improvisation, unconcerned with any preparatory or residual document, is completely at one with the non-documentary nature of musical performance and their shared ephemerality gives them a unique compatibility. So it might be claimed that improvisation is best pursued through its practice in music. And that the practice of music is best pursued through improvisation.
I believe the above to be true. But improvisation has no need of argument and justification. It exists because it meets the creative appetite that is a natural part of being a performing musician and because it invites complete involvement, to a degree otherwise unobtainable, in the act of music-making.”
“Limits and Freedom” from Improvisation: its nature and practice in music (2nd edition; 1992; The British Library)