Carl Reinecke was born in 1824 in Altona, Denmark. He studied first violin and then piano extensively, and began composing at age seven. He studied under Felix Mendelssohn, Robert Schumann and Franz Liszt, during the height of the German Romantic movement. He worked in Copenhagen as the Court Pianist from 1846 to 1848, when he left for Paris (likely due to the large number of revolutions occurring during that time in that part of the world, including in Copenhagen). He later moved to Leipzig and taught at the Leipzig Conservatory, where he taught students such as Edvard Grieg, Charles Villiers Stanford, Max Bruch, and others. His best-known work is the Undine sonata for flute.

Undine is based on a German romantic tale by Friedrich de la Motte Fouque. It tells the story of a water spirit named Undine, who seeks to join in love with a mortal man so that she may have an immortal soul. In the first movement we see Undine in her underwater life as she rides currents and plays in the waves. She then leaves the water kingdom in search of love, taking the form of a child, and is discovered by a fisherman and his wife, who have just lost their own daughter in a drowning. They choose to raise Undine as their daughter. This movement is set primarily in E minor, with large arpeggiated jumps in the flute melody to reflect the waves Undine played in, and fast sections of sixteenth notes showing the strength of the currents. The second movement, set primarily in B minor with lyrical portions in related keys, describes her continuing life with her new foster parents — she is carefree and mischievous, with a musical chase happening between the flute and piano. The piano has a folk-like solo section come in, which represents the knight Huldbrand, who seeks shelter from a storm with the fisherman’s family. He falls in love with Undine, and during the following flute melody that enters, her love awakens as well. The two chase each other throughout the movement, as Undine’s behavior is still erratic, and she seems to be able to control the weather. The third movement shows their married life together, which is peaceful and content, set in G Major. She explains to Huldbrand that she is a water spirit, afraid that he will see her differently, but he promises never to leave her. This is interrupted when, upon passing by a waterfall, Undine is rushed by water spirits, including her uncle, and she is afraid. They beckon to Undine to end her relationship with a mortal. Huldbrand tries to attack her uncle, but the spirits disappear into a waterfall. In the final movement, back in E minor, the couple takes a trip on the Danube in a boat, angering the water spirits. Undine is tossed overboard and sinks. Thinking his wife dead, Huldbrand plans to remarry, but on the night of his wedding Undine returns, this time as a spirit dressed in the clothes of a bride. Huldbrand begs Undine to show her face. She removes her veil and kills him with a kiss, drowning him in her tears. The piece ends with a beautiful melody in E major pulled from the moment in movement two in which Undine first fell in love with Huldbrand. At his funeral she transforms herself into a stream surrounding his grave, forever embracing him.