Helen of Troy 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. On the other hand, in the "Cypria", part of the Epic Cycle, Helen was the daughter of Zeus and the goddess Nemesis.
Ab ovo "soup to nuts". Thus "ab ovo" can also be used to mean a complete or entire thing. Ab ovo Ab ovo (Latin: "from the beginning, the origin, the egg") is a reference to one of the twin eggs from which Helen of Troy was born. The eggs were laid by Leda after mating with Zeus disguised as a swan. Had Leda not laid the egg, Helen would not have been born, so Paris could not have eloped with her, so there would have been no Trojan War. The English literary use of the phrase comes from Horace's "Ars Poetica", where