They say that long ago, before things were as they are today, the Moon fell in love with her brother.
She tried everything she could think of to get into his bed, but he was having none of it. Only Cat shared his bed, no one else.
So Moon goes to Cat one day and says: Cat, trade shapes with me.
And Cat, being Cat, says: What's in it for me?
Says Moon: Someday I shall bear a great many children, and my children will always make a place for you at their hearths.
And Cat, being Cat, says: What else?
Says Moon: Someday I shall bear a great many children, and my children will always make a place for you at their hearths. And they will always feed you what you most like to eat.
And Cat, being Cat, says: What else?
Says Moon: Someday I shall bear a great many children, and my children will always make a place for you at their hearths, and they will always feed you what you most like to eat. But though you live in their houses and eat their food and share their lives, yet you shall never belong to them, but only to yourself.
And Cat says: It's a deal.
So Cat and Moon traded shapes, and Moon got into her brother's bed after all. Of their love were born the witches of the world, and so to this day we keep cats at our hearths and feed them what they most like to eat. But though they live in our houses and eat our food and share our lives, yet somehow they never belong to us, but only to themselves.
Because that's the deal, and we're stuck with it.
Based on a Tuscan folk tale
For Magenta, who suggested it