In most sources, including the Iliad and the Odyssey, Helen is the daughter of Zeus, and Leda, the wife of the Spartan king Menelaus. Euripides' play Helen, written in the late 5th century BC, is the earliest source to report the most familiar account of Helen's birth: that, although her putative father was Tyndareus, she was actually Zeus' daughter. In the form of a swan, the king of gods was chased by an eagle, and sought refuge with Leda. The swan gained her affection, and the two mated. Leda then produced an egg, from which Helen emerged. The First Vatican Mythographer introduces the notion that two eggs came from the union: one containing Castor and Pollux; one with Helen and Clytemnestra. Nevertheless, the same author earlier states that Helen, Castor and Pollux were produced from a single egg.Pseudo-Apollodorus states that Leda had intercourse with both Zeus and Tyndareus the night she conceived Helen