Improvisation is a fundamental part of music-making - it even has a place in Western classical music, such as the freely invented cadenza in a piano concerto. Other musical traditions are fundamentally based in improvising, such as the classical Indian tradition, and jazz. In the 1950s, Free Improvisation developed from experiments in extending jazz, as an attempt to make music spontaneously with no reference to any style or tradition. David Toop has written a book about improvising, and Joelle Leandre has had a long career as a free improviser, playing with a wide variety of musicians around the world. But, she says, "we cannot be free...".