Hesiod, the Homeric Hymns and Homerica/Hymn XXXIII (To the Dioscuri)
TO THE DIOSCURI
Bright-eyed Muses, tell of the Tyndaridae, the Sons of Zeus, glorious children of neat-ankled Leda, Castor the tamer of horses, and blameless Polydeuces. When Leda had lain with the dark-clouded Son of Cronos, she bare them beneath the peak of the great hill Taÿgetus,—children who are deliverers of men on earth and of swift-going ships when stormy gales rage over the ruthless sea. Then the shipmen call upon the sons of great Zeus with vows of white lambs, going to the forepart of the prow; but the strong wind and the waves of the sea lay the ship under water, until suddenly these two are seen darting through the air on tawny wings. Forthwith they allay the blasts of the cruel winds and still the waves upon the surface of the white sea: fair signs are they and deliverance from toil. And when the shipmen see them they are glad and have rest from their pain and labour.
Hail, Tyndaridae, riders upon swift horses! Now I will remember you and another song also.