dance scene question

Hi,

Can somebody please answer a question for me? There is a scene where the mermaid is dancing with the prince. It is the part where they are having a party in the throne room in the castle and the princess and a bunch of guests are there. It is right before the witch enters the room and one of the other nobles almost gets into a fight with the prince. The mermaid dances with the prince and the musicians begin to play an instrumental song which is mostly lute/string instruments. I thought it was absolutely beautiful! Can somebody identify this song and tell me what it is? I love medieval/renaissance music and I would love to know what this song is. Is it a real song from this time period, or is it just something that the people who made the movie wrote? It sounds like a real song because it doesn't match the rest of the cheesy music that appears in the movie (by the way I love this movie though). Please let me know. Thank you, Alice.