Welsh mythology
Welsh mythology, also known as, consists of both folk traditions developed in Wales, and traditions developed by the Celtic Britons elsewhere before the end of the first millennium. As in most of the predominantly oral societies Celtic mythology and history were recorded orally by specialists such as druids. This oral record has been lost or altered as a result of outside contact and invasion over the years. Much of this altered mythology and history is preserved in mediaeval Welsh manuscripts, which include the Red Book of Hergest, the White Book of Rhydderch, the Book of Aneirin and the Book of Taliesin. Other works connected to Welsh mythology include the ninth-century Latin historical compilation Historia Brittonum and Geoffrey of Monmouth's 12th-century Latin chronicle Historia Regum Britanniae, as well as later Welsh folklore, such as the materials collected in The Welsh Fairy Book by William Jenkyn Thomas.
Cosmogony and creation
As with other Insular Celts, no direct written accounts of the origins of the cosmos survive. We can assume that these Celts did have a complex cosmogony, given the accounts from classical authors about the depth of knowledge of the druids who passed down their knowledge via orature.However, scholars can find connections to the broader Proto-Indo-European system in both the names of the deities themselves and in the later written tales that likely preserve remnants of the earlier orally transmitted narratives. Legends were not written down until after the Christianization of Britain, however, so these accounts are rather indirect; additionally, they likely evolved quite a bit over time anyway, as narrative systems typically do.
John T. Koch proposes that the name of the goddess Dôn, for instance, likely comes from *ghdhonos, meaning "the earth." In this sense she serves as the Welsh version of the *dheghom figure from Proto-Indo-European mythology, i.e. the primordial Earth Goddess from which all other gods originate. According to this theory, the Children of Dôn would be comparable to the Greek Titans.
John Carey suggests that the Fourth Branch of The Mabinogi, along with the Taliesin poems, contain hints of the cyclicality of cosmogonic progressions.
Claude Sterckx proposes that Celtic mythology hints at a cyclical cosmogony given a key commonly repeated story pattern: a man and woman face a rival for the woman's affection before uniting to birth a son who represents the life of the world; ultimately these figures die to create space for the cycle to repeat.
For instance, the names of certain Welsh mythological figures point to this pattern, as John Koch suggests that Gwron and Modron united to create Mabon.
This pattern occurs in The Mabinogion as well, with Pwyll and Rhiannon facing the rival Gwawl before uniting to conceive Pryderi. In both Mabon and Pryderi's cases, the divine son is taken by force soon after birth, with the divine parent needing to wait years before ultimately reuniting with the son.
With this in mind, the transformations of various characters hint not just at reincarnation but perhaps even reconfigurations of the cosmos itself.
Realms of existence
1) Elfydd: The Earth; the realm of humans2) Annwn: The Otherworld; the realm of the gods. Depending on the source, this could be a more typical Indo-European underworld where souls wait to be reincarnated, or the "deep" areas within the natural realm. Rather than being separate from nature, the Celts likely saw the Otherworld as being a mysterious but essential aspect of nature and a parallel to Elfydd.
While the sky and its celestial bodies are clearly separate from the earth, there does not seem to be an association between gods and the sky in extant Welsh myth, given the centrality of trees in Celtic knowledge, but there is no clear evidence for this.
Legends
Unlike the section above, we find the following legends in actual literary texts instead of etymological and mythical reconstructions by academic scholars.The Four Branches of the ''Mabinogi''
Four of the mythological stories contained in the Mabinogion are collectively known as the Four Branches of the Mabinogi. They concentrate largely on the exploits of various British deities who have been Christianized into kings and heroes. The only character who appears in every branch is Pryderi fab Pwyll, the king of Dyfed, who is born in the first Branch, is killed in the fourth, and is probably a reflex of the Celtic god Maponos. The only other recurring characters are Pryderi's mother Rhiannon, associated with the peaceful British prince Manawydan, who later becomes her second husband. Manawydan and his siblings Brân the Blessed, Branwen and Efnysien are the key players of the second branch, while the fourth branch concerns itself with the exploits of the family of Dôn, which includes the wizard Gwydion, his nephew, Lleu Llaw Gyffes, and his sister, Arianrhod.Pwyll, Prince of Dyfed
The first branch tells of how Pwyll, prince of Dyfed, exchanges places for a year with Arawn, the ruler of Annwn, defeats Arawn's enemy Hafgan, and on his return encounters Rhiannon, a beautiful maiden whose horse cannot be caught up with. He manages to win her hand at the expense of Gwawl, to whom she is betrothed, and she bears him a son, but the child disappears soon after his birth. Rhiannon is accused of killing him and forced to carry guests on her back as punishment. The child has been taken by a monster, and is rescued by Teyrnon and his wife, who bring him up as their own, calling him Gwri of the Golden hair, until his resemblance to Pwyll becomes apparent. They return him to his real parents, Rhiannon is released from her punishment, and the boy is renamed Pryderi.''Branwen ferch Llŷr''
In the second branch Branwen, sister of Brân the Blessed, king of Britain, is given in marriage to Matholwch, king of Ireland. Branwen's half-brother Efnysien insults Matholwch by mutilating his horses, and in compensation Brân gives Matholwch new horses and treasure, including a magical cauldron that can restore the dead to life. Matholwch and Branwen have a son, Gwern, but Matholwch proceeds to mistreat Branwen, beating her and making her a drudge. Branwen trains a starling to take a message to Brân, who goes to war against Matholwch. His army crosses the Irish Sea in ships, but Brân is so huge that he wades across. The Irish offer to make peace, and build a house big enough to entertain Bran, but inside they hang a hundred bags, telling Efnysien they contain flour, when in fact they conceal armed warriors. Efnysien kills the warriors by squeezing the bags. Later, at the feast, Efnysien throws Gwern on the fire and fighting breaks out. Seeing that the Irish are using the cauldron to revive their dead, Efnysien hides among the corpses and destroys the cauldron, although the effort costs him his life. Only seven men, all Britons, survive the battle, including Pryderi, Manawydan and Bran, who is mortally wounded by a poisoned spear. Brân asks his companions to cut off his head and take it back to Britain. Branwen dies of grief on returning home. Five pregnant women survive to repopulate Ireland.''Manawydan fab Llŷr''
Pryderi and Manawydan return to Dyfed, where Pryderi marries Cigfa and Manawydan marries Rhiannon. However, a mist descends on the land, leaving it empty and desolate. The four support themselves by hunting at first, then move to England, where they make a living by making, successively, saddles, shields and shoes. Each time their products are of such quality that local craftsmen cannot compete, and drive them from town to town. Eventually they return to Dyfed and become hunters again. A white boar leads them to a mysterious castle. Against Manawydan's advice, Pryderi goes inside, but does not return. Rhiannon goes to investigate and finds him clinging to a bowl, unable to speak. The same fate befalls her, and the castle disappears. Manawydan and Cigfa return to England as shoemakers, but once again the locals drive them out and they return to Dyfed. They sow three fields of wheat, but the first field is destroyed before it can be harvested. The next night the second field is destroyed. Manawydan keeps watch over the third field, and when he sees it destroyed by mice he catches their leader and decides to hang it. A scholar, a priest and a bishop in turn offer him gifts if he will spare the mouse, but he refuses. When asked what he wants in return for the mouse's life, he demands the release of Pryderi and Rhiannon, and the lifting of the enchantment over Dyfed. The bishop agrees, because the mouse is in fact his wife. He has been waging magical war against Dyfed because he is a friend of Gwawl, whom Pwyll, Pryderi's father, humiliated.Math fab Mathonwy
While Pryderi rules Dyfed, in the south of Wales, Gwynedd in the north of Wales is ruled by Math, son of Mathonwy. His feet must be held by a virgin except while he is at war. Math's nephew, Gilfaethwy, is in love with Goewin, his current footholder, and Gilfaethwy's brother Gwydion tricks Math into going to war against Pryderi so Gilfaethwy can have access to her. Gwydion kills Pryderi in single combat, and Gilfaethwy rapes Goewin. Math marries Goewin to save her from disgrace, and banishes Gwydion and Gilfaethwy, transforming them into a breeding pair of deer, then pigs, then wolves. After three years they are restored to human form and return.Math needs a new footholder, and Gwydion suggests his sister, Arianrhod, but when Math magically tests her virginity she gives birth to two sons. One, Dylan, immediately takes to the sea. The other child is raised by Gwydion, but Arianrhod tells him he will never have a name or arms unless she gives them to him, and refuses to do so. Gwydion tricks her into naming him Lleu Llaw Gyffes, and giving him arms. She then tells him he will never have a wife of any race living on Earth, so Gwydion and Math make him a wife from flowers, called Blodeuwedd. Blodeuwedd falls in love with a hunter, Gronw Pebr, and they plot to kill Lleu. Blodeuwedd tricks Lleu into revealing the means by which he can be killed, but when Gronw attempts to do the deed Lleu escapes, transformed into an eagle. Gwydion finds Lleu and transforms him back into human form, and turns Blodeuwedd into an owl, renaming her Blodeuwedd and cursing her. Gronw offers to compensate Lleu, but Lleu insists on returning the blow that was struck against him. Gronw pleads to be allowed to hide behind a rock when he attempts to kill him. Lleu agrees. He kills Gronw with his spear, which is thrown so hard it pierces him through the stone he is hiding behind.