Béla Bartók is regarded as one of the greatest composers of the twentieth century, the creator of a body of works as immense as it is complex. He was passionate about Hungarian folk music and carried out serious ethnological research in the field, his interest stemming not from romantic sentimentality, but from a fascination with it's simplicity and spontaneity. Bartók was constantly seeking to deepen his art as a composer, as can be seen from his numerous changes in style. From his final period comes the Concerto for Orchestra, a work which, more than any other perhaps, helped increase his popularity.