The Fourth Branch of the Mabinogi is the strangest and the most beautiful of the four, and at the centre of it is a young man called Llew Llaw Gyffes — the Bright One with the Steady Hand. His mother, Arianrhod, did not want him. She laid three impossible tynged (destiny-curses) on him: he would have no name unless she gave it, no arms unless she armed him, and no wife of any race that walked the earth.
His uncle, the magician Gwydion, broke every one of them. He tricked Arianrhod into naming the boy when she saw him hit a wren with a single stone — 'Llew Llaw Gyffes,' she said without thinking, and the name stuck. He tricked her into arming him by conjuring a phantom Saxon fleet outside her fortress. And for the third curse, he and Math fab Mathonwy gathered the flowers of the oak, the broom and the meadowsweet, and from them shaped a woman: Blodeuwedd, the Flower-Wife.
But Blodeuwedd was not loyal to the husband she had been made for. She fell in love with a hunter, Gronw Pebr, and together they plotted Llew's death. The trouble was that Llew could not be killed easily — not indoors and not outdoors, not on horseback and not on foot, not clothed and not naked, not by any weapon forged in the ordinary way. So Blodeuwedd coaxed the secret out of him as only a wife can.
He could only die, he told her, if he stood with one foot on the back of a goat and one foot on the rim of a bath built on a riverbank under a thatched roof, struck by a spear that had been a year in the forging — and only ever worked on during Sunday Mass.
She had Gronw forge the spear. She built the bath. She brought the goat. And there, on the only possible spot in the world where the only impossible death could happen, Llew was struck — and instead of dying, he transformed into an eagle and flew screaming into the oak woods.
Gwydion found him at last in the top branches of a rotting oak, sang him down with a magical englyn, restored him to human shape, and helped him take his revenge. Gronw was killed by a spear-throw at the same riverbank. Blodeuwedd was turned into an owl — and that, the Mabinogi tells us, is why owls are still hated by every other bird and only fly at night.
Wear Llew Llaw Gyffes and you wear the bright thread that runs through the whole Fourth Branch — the boy nobody wanted, who grew up to fly out of his own death and come back as a king.