Egeria

In Roman mythology, the goddess Egeria ("of the black poplar") was a goddess of birth, wisdom and one of the Camenae. She was married to Numa Pompilius, second king of Rome and taught him matters relating to being a wise and just king.

When Numa Pompilius died, she changed him into a well, located in the forest of Aricia, holy to Diana, in Latium.