In a way, the history of jazz's development is a small mirror of classical music's development through the centuries. Now jazz is a living form of original music, while classical music has gotten to the end of its cycle in terms of exploring its form.
I believe that historians and analysts of historical events need the authority of facts supplied by living witnesses to the events, which they make their subject.
The author knows just what he wants to illustrate and how he would like it to be done.