It actually drew on a much older tale from the Mabinogion....

Thanks, Mav, for relieving me from nightmares. I read through the information provided on the link you gave above, and read there a bit more about Lady Charlotte Guest's Mabinogion, which I cannot imagine pronouncing correctly! Ma-bih-NO-jyuhn is my best stab, and I probably just killed it!

Can't help thinking about my poor Demon I ran over--my beloved fat cat. Terrible thing to hurt an animal one loves, but to kill it--ah, that is woe.