Liszt, inspired by the composer Hector Berlioz, came up with the “tone poem,” a classical-music type that abandoned form to follow an idea within one movement. “In the so-called classical music the return and development of themes is determined by formal rules which are regarded as inviolable,” Liszt wrote in 1855. “In program music, in contrast, the return, change, variation and modulation of the motives is conditioned by their relation to a poetic idea.”
