Tales of the Enchanted Islands of the Atlantic

And while he was thus singing his verse near the door, there came suddenly a mighty storm of wind, so that the king and all his nobles thought the castle would fall on their heads. They saw that Taliessin had not merely been singing the song of the wind, but seemed to have power to command it. Then the king hastily ordered that Elphin should be brought from his dungeon and placed before Taliessin, and the chains came loose from his feet, and he was set free.