The Wild Swans of Coole

by William Butler Yeats;
The trees are in their autumn beauty,
The woodland paths are dry
Under the October twilight the water
Mirrors a still sky;
Upon the brimming water among the stones
Are nine-and-fifty Swans.

The nineteenth autumn has come upon me
Since I first made my count;
I saw, before I had well finished,
All suddenly mount
And scatter wheeling in great broken rings
Upon their clamorous wings.

I have looked upon those brilliant creatures
And now my heart is sore.
All's changed since I, hearing at twilight,
The first time on this shore,
The bell-beat of their wings above my head,
Trod with a lighter tread.

Unwearied still, lover by lover,
They paddle in the cold
Companionable streams or climb the air;
Their hearts have not grown old;
Passion or conquest, wander where they will,
Attend upon them still.

But now they drift on the still water,
Mysterious, beautiful;
Among what rushes will they build,
By what lake's edge or pool
Delight men's eyes when I awake some day
To find they have flown away?

The swan is a noble and beautiful bird, it is also a mythological bird caught up in the celtic story of The Children of Lir, it can also be found in the German 13th century tale of the Swan Knight and of course in the Grimm's story of the six brothers who having been turned into swans by their evil godmother, can only be released by their sister,who must not speak for 6 years and must make each brother a shirt of nettles.She does this but unfortunately has not enough time to finish the arm of the last shirt, so that this brother is left with a swan's wing.
According to Ann Ross, the swan in its early conception of bronze age history represented the sun, and came to be portrayed as one of the creatures pulling the sun chariot from the bronze age, only later during the celtic period did it become more abstract.
There is even a pair of swans found in rock art in Norway, they are clearly distinguishable as swans because of their long beaks, necks and heavy bodies.
Birds were important motifs to be found in celtic artwork, the little duck on flagon handles or swans holding chains in their beak on horse furnishings. And there is a tale told of Cu Cuchlainn that of having decapitated the three heads of the sons of an enemy, on returning in his chariot drawn by horses, he spied some deer which he duly caught and tied them to the chariot. He then brought down alive with stones from his sling, first 8 swans and then 16 swans, which he fastens also to the chariot and then proceeded to Emain Macha.
Shapeshifting or the metamorphising of human to animal can be found in the "Tale of Angus", written down in the 8th century. Swans are often described as having a silver or gold chain round their necks and in the tale of Angus, he falls in love with a particular girl called Caer. But is told that she is a powerful magical being who, one year is a human and the next a swan. She is surrounded by 150 other girls, her followers. Her transformation takes place at the pagan festival of Samhain (November 1st) at Loch Bel Dracon.
Her magic is weaker when she takes the form of a swan, and Angus goes to the loch and sees the 150 swans with silver chains and golden ringlets with Caer being taller than the rest. He also changes into a swan and they fly round the loch together three times. It must also be noted that they also cast a spell of sleep for three days over the countryside whilst they fly to his palace.
The anglo saxon for swan is Ielfetua, and the tale of the Swan Knight also rest on an Scandinavian story found in the earlier story of Beowulf. Here it is told that a boat once arrived at Scandia with a young boy in it, he was called Scild, the son of Sceaf, he became educated by the people and became their king. And in Beowulf it is said that Scild reigned long and when he was about to die, wished to be laid in a boat fully armed and sent out to sea; other legends say that he was drawn by swans.

Hung with hard ice-flakes,
where hail-scur flew,
There I heard naught save the harsh sea
And ice-cold wave, at whiles the swan cries,
Did for my games the gannet's clamour,
Sea-fowls, loudness was for me laughter,
The mews' singing all my mead-drink.
Storms, on the stone-cliffs beaten, fell on the stern
In icy feathers; full oft the eagle screamed
With spray on his pinion.

Taken from the "Seafarer"

the Anglo-Saxons believed that the swan's wings produced music in flight and the loud rhythmic throbbing sound of the flight of the Mute Swan, Cygnus olor differentiates it from the Whooper Swan, Cygnus cygnus whose wings produce a quieter swishing sound.