Undine is an opera in four acts by Albert Lortzing. The German libretto was by the composer after Friedrich de la Motte Fouqué's story of the same name.
There had been a revival of interest in Fouqué following the writer's death in 1843 to which Lortzing responded. Unlike Lortzing's earlier comedies, this work is a serious one, described as a romantische Zauberoper ('romantic magic opera').
A number of other operas and ballets have been based on Fouqué's version of the myth of the water spirit Ondine, including Tchaikovsky's Undina, E T A Hoffmann's Undine, Cesare Pugni's Ondine and Hans Werner Henze's Undine.
The opera was first performed at the Nationaltheater in Magdeburg, on 21 April 1845
The knight Hugo von Ringstetten, having won a tournament, has been given a quest by Bertalda, the daughter of the Duke. She wants him to explore the enchanted forest. Hugo and his squire Veit have been forced by bad weather and floods to take refuge in a fishing village, and have been living there for some months. Hugo has fallen in love with the beautiful Undine, the foster daughter of the fisherman Tobias and his wife Marthe, and plans to marry her. He tells his bride of his previous life and that he had once loved Bertalda, but now has forgotten her. They are astonished at Undine's remark that she has no soul.
As farmers and fishermen follow the knight and Undine into the Chapel, Kühleborn, the Prince of the water spirits, suddenly appears, disguised as a farmer, and talks to Veit. He remarks that this Undine is probably only a creation of his Lord and will not be permanent. Kühleborn had once kidnapped the real daughter of the fishermen, Bertalda, and entrusted her to the Duke. Undine was left for Tobias and Marthe to raise instead. He wanted to test whether the people who have a soul, are better off than the soulless spirits that live in the waters. He decides to watch over Undine and accompanies the young couple and Veit to the imperial capital, disguised as a priest.