<P> Gilfaethwy, nephew to the Venedotian king, Math fab Mathonwy, falls in love with his uncle's virgin foot - holder, Goewin . His brother Gwydion conspires to start a war between the north and the south, so as give the brothers the opportunity to rape Goewin while Math is distracted . To this end, Gwydion employs his magic powers to steal a number of otherworldy pigs from the Demetian king, Pryderi, who retaliates by marching on Gwynedd . Meanwhile, Gwydion and Gilfaethwy attack and rape Goewin . </P> <P> Pryderi and his men march north and fight a battle between Maenor Bennardd and Maenor Coed Alun, but are forced to retreat . He is pursued to Nant Call, where more of his men are slaughtered, and then to Dol Benmaen, where he suffers a third defeat . To avoid further bloodshed, it is agreed that the outcome of the battle should be decided by single combat between Gwydion and Pryderi . The two contenders meet at a place called Y Velen Rhyd in Ardudwy, and "because of strength and valour and magic and enchantment", Gwydion triumphs and Pryderi is killed . The men of Dyfed retreat back to their own land, lamenting over the death of their lord . </P> <P> When Math hears of the assault on Goewin, he turns his nephews into a series of mated pairs of animals: Gwydion becomes a stag for a year, then a sow and finally a wolf . Gilfaethwy becomes a hind deer, a boar and a she - wolf . Each year they produce an offspring which is sent to Math: Hyddwn, Hychddwn and Bleiddwn . After three years, Math releases his nephews from their punishment and begins the search for a new foot - holder . Gwydion suggests his sister Arianrhod, who is magically tested for virginity by Math . During the test, she gives birth to a "sturdy boy with thick yellow hair" whom Math names Dylan and who takes on the nature of the seas until his death at his uncle Gofannon's hands . </P> <P> Ashamed, Arianrhod runs to the door, but on her way out something small drops from her, which Gwydion wraps up and places in a chest at the foot of his bed . Some time later, he hears screams from within the chest, and opens it to discover a baby boy . Some scholars have suggested that in an earlier form of the Fourth Branch, Gwydion was the father of Arianrhod's sons . </P>

How did math discover aranrhod had lost her virginity