Nielsen began working on his sixth and final symphony in summer 1924 and continued into the autumn. He was interrupted by a long journey abroad in the beginning of 1925 but continued on the symphony after the journey, finishing the third movement in April. During the summer he stopped but must have been under way with the work again in October. The final movement is end-dated 5 December 1925, a week before the first performance. The title of the symphony, Sinfonia semplice, was not used in musical sources during Nielsen's lifetime. However, it was printed in the concert programme for the first performance. Nielsen also mentioned the title in an interview given two days before the premiere. See more about this work at The Royal Library