By Dr Oliver Tearle (Loughborough University)
Who were Castor and Pollux and what are the details of the story involving these two figures from Greek mythology? These two Greek heroes, who are now perhaps most familiar to people because they became immortalised in the constellation Gemini in the night sky, are the subject of a fascinating story, or rather series of stories, from ancient Greek mythology, so let’s take a closer look at the details of the myth.
Before we offer an analysis of the Castor and Pollux story, it might be worth summarising the plot.
Castor and Pollux myth: plot summary
The story of the Greek god Zeus adopting the form of a swan and visiting the woman Leda and coupling with her is well-known. What is also fairly well-known to fans of classical myth is that this union between Leda and swan-shaped Zeus resulted in Leda conceiving a child, who became Helen of Troy. W. B. Yeats treats this myth, and the dramatic ramifications of it resulting in the Trojan War, in his sonnet, ‘Leda and the Swan’.
But what is less well-known is that Zeus and Leda’s union resulted in the conception of another child, a boy who was named Pollux. (He was actually known as Polydeuces to the Greeks, but we almost always refer to him now by his Latin name, Pollux.)
But there’s more. On the same night that Leda conceived Helen and Pollux with Zeus/the swan, she also lay with her husband, King 
Tyndareus of Sparta, and conceived twins with him as well. These twins were named Castor and Clytemnestra.
Both Helen and Clytemnestra would play important roles in the legends surrounding the Trojan War. But the focus of this summary and analysis is, of course, the two boys: Castor and Pollux. What became of them?
These two twins were known collectively as the Dioscuri, meaning ‘sons of Zeus’. Of course, this is only partly true, since Castor was actually the (mortal) son of Tyndareus, at least in many versions of the myth. But the two young men were inseparable and were both famed in their home city of Sparta for their skill and bravery. They were both known for their skill as fighters, with Pollux being especially renowned for his skilful boxing.
One day, their sister, Helen – later to become known as Helen of Troy – was kidnapped. No, not by Paris, the Trojan prince (that was to come later), but by Theseus, the hero who slew the Minotaur in the Labyrinth. Theseus imprisoned Helen in a fortress and then went to the Underworld to ask for Persephone’s hand in marriage. While he was absent, Castor and Pollux seized their chance – and their sister.
Once they had set Helen free, their usurped Theseus’ son, who was minding the throne of Attica in his father’s absence, and put another man in charge of the kingdom. They then kidnapped Theseus’ mother, Aethra, and took her back to Sparta with them.
This story illustrates both how brave and resourceful the twins were, but also how close they were, capable of working together to achieve a common aim. Such characteristics are also present in their other adventures, such as when, in the story of Jason and the Golden Fleece, they saved the ship, the Argo, from a storm.
Their other most famous adventure, however, involves their part in the battle of Lake Regillus, in which they fought alongside the newly established Roman Republic against their enemies, the Latin League.
When Castor died, Zeus gathered Pollux up into heaven so the two brothers could be together. But Pollux didn’t want to be apart from his twin. Zeus, understanding this, decreed that for half the year – on every other day – the two brothers would be together with the gods up in heaven. They became the constellation Gemini – ‘the twins’.
Castor and Pollux myth: analysis
In fighting alongside the Romans against the Latin League, Castor and Pollux played an important role in the establishment of the Roman Republic. Rome built them a temple in the Forum, which was a high honour indeed given they were foreign-born fighters. The story of Castor and Pollux is thus bound up with the myth of the founding of Rome.
The story of how Castor and Pollux both rescued their sister (or half-sister) Helen after she was whisked off by Theseus acts as an important forerunner to the events which prompted the Trojan War. Indeed, in Homer’s Iliad, the most famous account of the Trojan War in classical Greek literature, Helen looks down from the walls of Troy and remarks that she cannot see her brothers coming to fight for her:
I see, moreover, many other Achaeans whose names I could tell you, but there are two whom I can nowhere find, Castor, breaker of horses, and Pollux the mighty boxer; they are children of my mother, and own brothers to myself. Either they have not left Lacedaemon, or else, though they have brought their ships, they will not show themselves in battle for the shame and disgrace that I have brought upon them.
The narrator tells us that Castor and Pollux are, in fact, already dead and buried back in their homeland, Lacedaemon.