Toscanini was often criticized for not performing much American music and contemporary music ( music by living composers ) . However , in 1938 , he conducted the world premieres of two orchestral works by Samuel Barber , Adagio for Strings and Essay for Orchestra ( Barber ) Essay for Orchestra . Toscanini was often criticized for neglecting American music ; however , on November 5 , 1938 , he conducted the world premieres of two orchestral works by Samuel Barber , Adagio for Strings and Essay for Orchestra .