Br J Ophthalmol 96:161 doi:10.1136/bjophthalmol-2011-301442
  • Cover illustration

The Graeae sisters: one eye for three

The phenomenon of reflection lies at the heart of our ability to see objects. Almost all natural light emanates from the stars including the sun. Light reflected from objects is focused on the retina of the eye creating images that allow the beholder to perceive objects. Light, reflection and eye(s) make intriguing ingredients of many legends in mythology as illustrated in the following story:

When King of Argos, Acrisius, visited the Oracle at Delphi, it was prophesised that he would die at the hands of his daughter's son. His daughter, Danae, was childless at the time and in order to ensure she did not bear a son, Acrisius imprisoned her. However, the Greek god Zeus, came to Danae as a ‘shower of golden rain’ in the prison and a son, Perseus was born to Danae.1

Acrisius learnt of this and locked both the mother and son into a wooden chest and set them afloat in the deep sea. The wooden chest drifted to the island of Seriphos where they were discovered by a fisherman, Dictys. Dictys' brother, Polydectes, was the king of the island. Over time, the king started to woo Danae, but Perseus was wary of him and tried to keep Danae away from Polydectes.

Polydectes therefore designed a plan to humiliate Perseus such that he would leave the island. He held a large banquet under the pretense that he was betrothed to another, Hippodamia. Polydectes knew that Perseus would be obliged to bring a gift but had nothing to give, which would humiliate him. The defiant Perseus attended the banquet and promised Polydectes to bring him anything he desired. Polydectes demanded the head of the Gorgon Medusa whose very glance turned a person to stone, not expecting Perseus to return from the quest.

The goddess Athena, who was watching over Perseus, gave him a shiny shield and a sharp sword and advised him to find the Hesperides nymphs, as they possessed what was required to defeat Medusa. Athena guided Perseus to the Graeae sisters who knew the location of the Hesperides. The three Graeae sisters shared one eye between them and were well known for fighting among themselves to hold the eye, as they did not have vision without it. They refused to give Perseus the information he required so Perseus stole the eye from them as they were passing it to one another and held it ransom in exchange for the knowledge of the whereabouts of the nymphs. Figure 1 (and the cover image) illustrates the scene of Perseus stealing the eye from the Graeae sisters. The Graeae led Perseus to the Hesperides, from whom he obtained a cap to hide himself from Medusa's sisters, a pair of shoes-of-swiftness to make good his escape and a special bag to safely contain Medusa's head.2 When Perseus came across the cave in which Medusa was asleep, Perseus used his shield to look at Medusa's reflection in the shield so that he was not turned to stone. He beheaded Medusa with his sword and stored her head safely in the special bag to return to the island of Seriphos.

Figure 1

Perseus stealing the only eye shared by the three Graeae sisters. Translation of the Latin text (Courtesy Lara Kennedy): Perseus set out, equipped with advice and weapons from Pallas. The Graeae, with only a single eye, showed him the sanctuary of the nymphs. Immediately, his feet winged, the Gorgon head was revealed in the shadows. The mortal carried a single sword against the immortal. Both the Gorgon's sisters rose and closely pursued him. Having looked at terrible Medusa in the mirror he struck and seized the serpent, and now rocky Atlas and the followers of Phineus were turned to stone for the sake of the girl Andromeda.

His return journey took him to Ethiopia where he saved the princess Andromeda from a sea serpent and married her. When he returned to Seriphos he found that Polydectes had been treating his mother badly. He entered Polydectes court room and pulled out Medusa's head from the bag turning Polydectes into stone.


  • Provenance and peer review Commissioned; internally peer reviewed.

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