Early in 1865, together with Horneman, Hornbeck and Matthison-Hansen, Grieg and Nordraak founded ‘Euterpe’, a society dedicated to the promotion of contemporary Scandinavian music, borrowing the name from a similar organization in Leipzig. Concerts were given between March 1865 and April 1867, though with less frequency towards the end. In one of its early programmes, on 1 April 1865, the second and third movements of Grieg's symphony were performed. Being in frequent company with Nordraak helped to bring out Grieg's talents and led to the Humoresker, op. 6, four piano pieces which were a major breakthrough for the composer's national style. Grieg wrote to Aimar Gronvold, ‘Now there came a happy time of joy and productivity. This was in 1864–5. In a short time in Copenhagen, during daily company with Nordraak and the Scandinavian-inspired young people, I wrote many songs, the Humoresker op. 6, Sonata op. 7 [for piano] and Sonata op. 8 [for violin].’

As far as the songs are concerned, it was the four published as op. 5 that really began to show signs of the maturing composer and in which Grieg succeeded for the first time in finding his true self and a personal form of expression. They come like a breath of spring sunshine, light of heart and melodically beautiful, and two of them may be counted amongst his best songs. The texts Grieg chose to set came from a collection of eight short love-poems by Hans Christian Andersen, Hjertets Melodier (Melodies of the Heart), written in 1830, which were the result of Andersen's love for Riborg Voigt. At the time of their meeting, she was unofficially engaged to someone else and, although obviously attracted to Andersen, she married her fiance six months later. Andersen tried to comfort himself with the idea that Riborg had really loved him and married only out of duty, and during the next few months he wrote a large number of rather melancholy poems, the best of which were published in the collection. In January 1831 a new volume, Fantasier og Skitser (Fantasies and Sketches), was published, which included these Hjertets Melodier and all his love-poems to Riborg Voigt.