The Little Mermaid becomes melancholic and asks her grandmother if humans can live forever. The grandmother explains that humans have a much shorter lifespan than a mermaid's 300 years, but that, when mermaids die, they turn to sea foam and cease to exist, while humans have an eternal soul that lives on in heaven. The Little Mermaid, longing for the prince and an eternal soul, visits the Sea Witch who lives in a dangerous part of the ocean. The witch willingly helps her by selling her a potion that gives her legs in exchange for her tongue and beautiful voice, as the Little Mermaid has the most enchanting voice in the world. The witch warns the Little Mermaid that once she becomes a human, she will never be able to return to the sea. Consuming the potion will make her feel as if a sword is being passed through her body, yet when she recovers, she will have two human legs and will be able to dance like no human has ever danced before. However, she will constantly feel as if she is walking on sharp knives. In addition, she will obtain a soul only if she wins the love of the prince and marries him, for then a part of his soul will flow into her. Otherwise, at dawn on the first day after he marries someone else, the Little Mermaid will die with a broken heart and dissolve into sea foam upon the waves.