From the recording Orpheus Tamed the Animals
Leda was a daughter of Thestius, the King of Pleuron; Thestios being famous as the uncle of Meleager in the story of the Calydonian Hunt.
When of age, Leda was married to King Tyndareus of Sparta; Tyndareus having been placed on the throne by Heracles.
Leda was a beautiful woman, and her beauty attracted the attention of Zeus, who spied her from his throne on Mount Olympus. The beauty of Leda roused Zeus to action, and the god transformed himself into a magnificent swan. Then, portraying himself as a bird escaping from a bird of prey, Zeus lay down next to Leda, and impregnated her!
Leda would subsequently produce one or two eggs, from which four offspring were born; the children being Helen, Clytemnestra, Castor and Pollux [Source: https://www.greeklegendsandmyths.com/leda.html]
Rather appropriately, this piece is performed on my lovely Luthieros swan-necked lyre.