Leda (mythology)

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Leda (mythology)
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In Greek mythology, Leda was the mother of Castor and Pollux. Their father, the god Zeus, had taken the form of a swan when they were conceived. (PROSE: Wooden Heart)

Achilles reminded the First Doctor (whom he believed to be Zeus) that he appeared to Leda in the form of a swan. (TV: The Myth Makers)