There is a curious section in Aradia: Gospel of the Witches by Charles Leland that describes the goddess Diana’s incarnation in human form and her marvelous spellcasting to impress the witches. The passage says that “she declared that she would darken the heavens and turn all the stars into mice.” Diana duly accomplishes this feat, the heavens rain with mice, and Diana is crowned Queen of the Witches.
So why does Diana make it rain mice, of all things, to impress the witches? The answer lies in the dual roles of Apollo, as god of light and god of mice. Possibly these roles became syncretized with Apollo as he absorbed many other gods, but at any rate Diana was turning the stars (light) into another of their forms: mice. This is why Diana once chose to make it rain mice.