An answer can be found in a story from the western highlands of Scotland. In a great assembly of all the birds of the air, it was decided that the sovereignty of the feathered tribe should be given to the bird who could fly the highest. The favourite was naturally the eagle, who immediately began his flight toward the sun - fully confident in his ability to win the title of King of the Birds. When he found himself soaring high above all his competitors, he proclaimed in a mighty voice his monarchy over all creatures who had wings. But suddenly, from out of his wings popped the wren, who had hidden himself under the eagle's feathers. He flew a few inches higher and chirped out loudly, 'Birds, look up and behold your king!'This story shows the wren as a cunning bird, prepared to build on the achievements of others and to mock their pride by outwitting them at the final moment. The Druid was known as the 'cunning man' - the man who can become invisible like the wren, who can travel on the back of the noble eagle to reach his destination, saving himself energy in the process. Being small he is unobtrusive and being small he can enter worlds that bigger people cannot. Being proud makes one unwieldy; being small and humble enables one to slip through the eye of a needle or down the root of a tree.
The Breton Celts go even further in according the wren a key role in their bird-lore: they say that it was the wren who brought fire from heaven, but that as she flew back down to earth her wings began to burn and she had to pass her gift to the robin, whose plumage also burst into flames. The lark then came to the rescue, finally bringing the gift of fire to the world.
The Druid's house is the wren's nest - a place of comfort and safety, for another important symbol in Druidry is the egg. The Druid's Egg, made famous by Pliny's remarks, articulates the idea that in order to grow and change there is required periods of incubation - withdrawing from the world to allow the opportunity to reform in the womb of time. The wren's nest was said to be protected by lightning. Whoever tried to steal wren's eggs or baby wrens would find their house struck by lightning and their hands would shrivel up.
On the Isle of Man a story is told of a fairy-girl or mermaid who lured youths into the sea. One of them threw a spear at her and to avoid it she turned herself into a wren, but she was obliged to assume her own shape on each New Year's Day. On that day she was at the mercy of her hunters who, if they were able, could kill her. A wren's feather became a lucky charm to preserve sailors from drowning and no Manxman would go to sea without one.
The tradition of wren-hunting took place on New Year's Day until the Feast of the Wren was transferred to St. Stephen's Day on December 26th. With this tradition the wren has become a god or king rather than a mermaid - for the wren was hunted and killed in a ritualistic way, enacting the idea that the death of a god bestows strength on his killer, a variant of the belief that in the killing of the old king, his powers will be passed on to his successor.
The wren symbolised wisdom and divinity. It is difficult to actually see a wren. At New Year the apprentice Druid would go out by himself into the countryside in search of hidden wisdom. If he found a wren he would take that as a sign that he would be blessed with inner knowledge in the coming year. Finding a creature small and elusive to the point of invisibility was a metaphor for finding the elusive divinity within all life. (Geocities)
