Improvisation was born long before written music. All the classics and romantics improvised. Beethoven became known for his improvisations, Chopin and Liszt made the show in the salons. It has been relegated since the end of the nineteenth century to the second rank in Western music, Wagner rightly considered that one could not improvise music worthy of the name with a large workforce without generating a cacophony, and it did not bring anything to the publishers! Jazz and trad music have brought it up to date. It's like composition, but in real time, without the ability to erase, to go back. The gesture is no less elegant, as long as we are attentive to certain starting principles. Then anything can happen!