Leda is a woman in Greek myth — the wife of Tyndareus, king of Sparta. The story people always tell about her is this: the god Zeus wanted her, so he turned himself into a swan, a big white water bird, and came to her in that shape. From that night, and from the same night with her husband, came four famous children — Helen, whose beauty later started the Trojan War; Clytemnestra; and the twin brothers Castor and Pollux. In some versions Leda lays eggs, which is why old paintings sometimes show eggs beside her. You do not need this word to talk about your day. You need it because it is everywhere in Western art and writing. 'Leda and the Swan' is the name of dozens of famous paintings and sculptures, and of a very well-known poem by the Irish poet W. B. Yeats. When a museum label or an article says 'Leda', it is pointing at that scene. It is worth being honest with students about what the story is. Older books call it a seduction or a love story, and the paintings are often beautiful and calm. Zeus takes the shape of an animal so that Leda cannot refuse or even understand what is happening, and modern readers — including Yeats — read the scene as violence, not romance. Both readings are out there, and you will meet both. The name is also used in astronomy: Leda is one of Jupiter's small moons, named, like Jupiter's other moons, after someone Zeus (Jupiter to the Romans) pursued.