<P> Arianrhod (Welsh pronunciation: (arˈjanr̥ɔd)) is a figure in Welsh mythology who plays her most important role in the Fourth Branch of the Mabinogi . She is the daughter of Dôn and the sister of Gwydion and Gilfaethwy; the Welsh Triads give her father as Beli Mawr . In the Mabinogi her uncle Math ap Mathonwy is the King of Gwynedd, and during the course of the story she gives birth to two sons, Dylan ail Don and Lleu Llaw Gyffes, through magical means . </P> <P> According to the Fourth Branch, Arianrhod's uncle Math fab Mathonwy would die if he did not keep his feet in the lap of a virgin when he was not at war . Gilfaethwy conceives a lust for Math's original footholder, Goewin, and he and his brother Gwydion engineer a war with King Pryderi of Dyfed, forcing Math to leave his court . In Math's absence Gilfaethwy rapes Goewin . When Math returns he punishes his nephews severely by turning them into a series of mated pairs of animals, and marries Goewin to alleviate her shame . However, he must find a new virgin to hold his feet . </P> <P> Gwydion suggests his sister, Arianrhod . To test her virginity, Math tells her to step over his magician's rod . On doing this, however, she immediately gives birth to a young boy, Dylan ail Don, and a blob - like entity which becomes Lleu Llaw Gyffes . Dylan is a sea spirit, who flees to the ocean immediately after he is baptized; Gwydion grabs the entity before anyone else sees it and places it in a chest . Before long it becomes a boy who grows at twice the normal rate; when he is four he is as big as an eight - year - old . Gwydion takes him to see his mother at her home, Caer Arianrhod . </P>

Where does king math have to keep his feet