Leda, daughter of Thestius, was pledged in marriage to Tyndareus, heir to the Spartan throne. Now on the night their marriage was to be consummated, Leda went out and found a beautiful, snow-white swan being pursued by an eagle. This swan took refuge in Leda's embrace and so she took it back to the royal palace, for she had never seen such a lovely swan before. On the same night she consummated her marriage with Tyndareus, she heard a tapping at her window, and a most elegant honk from the swan she had rescued earlier. Still beautiful although exposed to the elements, she went outside to check up on her new pet. When Leda stared into its eyes, Cupid sent an arrow of purest gold straight into her heart. And so it was that Leda found herself coupling with two different beings that night - a man and a god. She later hatched eggs which gave birth to the mortal siblings Clytemnestra and Castor and the divine siblings Helen and Pollux.