Last weekend I spent two days before the Muenster Jazz Festival at a seminar learning about improvisation. One of the most fascinating sessions was about improvisation in the nineteen century. Composers such as Beethoven and Liszt were leading exponents and writers like Czerny explained how it was possible to "extemporise". Certainly it went hand in hand with the rise of the Romantic individual and was as much a means of expression as poetry or art. Especially helped by the improvements in the piano. (Much easier to appreciate and develop than two hours of wailing oboe improvisation!)
It's a skill that was lost during the 20th century as classical musicians concentrated more on technique and interpretation. Improvisation was frowned upon, except perhaps by organists. Until jazz came along to save it. Hence one partly sees, in my view, why jazz musicians have been at the forefront in highlighting human rights and so on. (Weren't Max Roach and Nina Simone two of the leaders propounding civil rights in the 60s?)
By the way. Thinking further on the matter, there is one further element of jazz which has developed in Western culture which wasn't around in the 19th century - the concept of improvisation within a group context. So we end up with a melding of approaches from western and eastern cultures.