23, is the incidental music to Henrik Ibsen's 1867 play Peer Gynt, written by the Norwegian composer Edvard Grieg in 1875.

However, it was much more difficult for Grieg than he imagined, as he wrote to a friend: "Peer Gynt" progresses slowly, and there is no possibility of having it finished by autumn.

It is a terribly unmanageable subject.Nina Grieg, his wife, wrote of Edvard and his music: The more he saturated his mind with the powerful poem, the more clearly he saw that he was the right man for a work of such witchery and so permeated with the Norwegian spirit.

[4]Even though the premiere was a "triumphant success", it prompted Grieg to complain bitterly that the Swedish management of the theatre had given him specifications as to the duration of each number and its order: I was thus compelled to do patchwork...

[8] (See the article on Ibsen's play for a list of notable productions, including concert performances of the incidental music.)

It was originally orchestrated for: one piccolo, two flutes, two oboes, two clarinets in A, two bassoons, four horns in E, two trumpets in E, three trombones, a tuba, timpani, cymbals, bass drum, triangle, harp, and strings.

Over a decade after composing the full incidental music for Peer Gynt, Grieg extracted eight movements to make two four-movement suites.