goo-ID-yon, GWID-yon, GWID-ee-on, goo-ID-ee-on

The meaning is difficult to explain. The word "gwyddion" means "trees" or "forest" {a more common word is goddeu, which is related}, but can also mean "weaver" and "loom." A related word, "gwyddonydd," means "scientist." Now, taking into consideration that the word Druid--magician, priest, and judge of Celtic society--is thought to derive from "drus" meaning oak, it is likely that the word for scientist is derived from forest--the man of learning gained his learning from nature. Hense, the name implies one who is learned, steeped in knowledge both esoteric and scientific, and weaves his way in spells and science, rather like an alchemist.

That said, there are two figures named Gwydion to recount, the second based upon the first:

1. Gwydion son of Don and Beli. He figures in the story Math fab Mathonwy, fourth branch of the Mabinogi (The Mabinogion). He is the trickster figure of the pantheon of the Children of Don, a complex figure with both good and bad qualities. When his brother Gilfaethwy falls in love with the maiden Goewin, Gwydion creates a war to distract his uncle Math ap Mathonwy, her guardian, so that Gilfaethwy could rape her. This war also succeeds in stealing Pryderi's magic swine of Annwfn (Annwn) by way of magic trickery, and in the murder of Pryderi (who was of the Children of Llyr) by Gwydion.

These actions lead Math ap Mathonwy to exile Gwydion and his brother Gilfaethwy from Caer Dathyl. More humiliating, the brothers are turned into wolves, pigs, and deer, alternating their genders and being forced to copulate with each other.

Upon returning to the court after three years, Gwydion learns that Math must replace Goewin's place as royal footholder with a new virgin. Gwydion suggests his sister Arianrhod. However, when Math tests her by making her jump over his magic wand (boy, if that isn't loaded with sexual imagry), she suddenly gives birth to two sons. (There is some implication that the children may be Gwydion's.) The first is named Dylan Eil Ton, who immediately sets out to sea. The second is quickly grabbed by Gwydion before Arianrhod has a chance to kill it, and he sends the child to a wetnurse.

A feud having now broken out between Arianrhod and Gwydion, she refuses to name the boy. However, he tricks her by presenting the boy as a stranger. She names him Lleu Llaw Gyffes (sometimes spelled Llew Llaw Gyffes), but curses him, saying he will never gain armes. Again, Gwydion disguises the boy, and she unknowingly gives him armes. Again, the boy is revealed as her son. She lays the third curse on him, that he would never have a wife born of man. So, Gwydion and Math decide to construct a wife made out of flowers for young Lleu. Calling her Blodeuwedd (meaning "flowerface"), they marry her off to the young man.

Unfortunately, she rebels and find out how her lover can kill Lleu. However, after Lleu is attacked, Gwydion changed him into an eagle, which hides then in an oak tree. Lleu is then changed back to a man by Gwydion, and nursed to health. Gwydion then changes Blodeuwedd into an owl, and has Lleu kill her lover Gronw.

Here the story ends. Gwydion's other appearances are mainly in the poetry attributed to Taliesin in The Book of Taliesin. These poems seem to be of a later date than the sixth century, however. They speak of Gwydion's power as a magician, often bringing up the creation of Bloddeuwedd. The most prominent is the poem "Cad Goddeu--The Battle of the Trees." Other poems which mention him are "The Chair of Cerridwen" and "Song Before the Sons of Llyr," among many others.

2. Prince Gwydion ap Don from The Prydain Chronicals by Lloyd Alexander. Here, Prince Gwydion is heir apparent to High King Math Mathonwy. He is mentor to young Taran, and generally looses his nastier side, while retaining his magical abilities. He weilds the sword Dyrnwyn and is in constant battle with both Arawn and Pryderi, both of whom are much darker figures in the series than in Celtic Mythology.