Cap of Hades

Also Known As: Greek Aidos kynee, literally the dog-skin cap of Hades; also Helm of Hades, Helmet of Hades, Cap of Invisibility
Region/Culture: Southern Europe
Mythos: Greek Mythology
Primary Type/Nature: Mythological Objects
Mythical Attributes: The cap makes whoever wears it invisible to gods, monsters and mortals alike, while leaving the wearer’s own sight untouched.
Role in Mythos: It is the gift the Cyclopes made for Hades in the war against the Titans, and the borrowed advantage behind Athena’s wounding of Ares and Perseus’s escape from the Gorgons.
Relation to Humans: Only one mortal, Perseus, is ever said to have worn it, and he had it on loan and gave it back. For ordinary Greeks it survived as a figure of speech for anyone who hides behind a trick.

Dust hangs over the plain of Troy, and in the middle of it the god of war is bent over a dead man, stripping the armour from a huge Aetolian named Periphas. He does not look up. He has no reason to. The chariot rolling toward him carries a mortal, Diomedes, and gods do not flinch at mortals. What Ares cannot see is the second figure in the car, the one who has shoved the driver out and taken the reins herself, so that the oak axle groans under a weight no human passenger could put on it. Athena is wearing the cap of Hades, and as far as Ares can tell, she is not there at all.

That is the oldest surviving appearance of the object, in the fifth book of the Iliad, and it is over in a line and a half. Homer does not explain where the goddess got it or how it works. He assumes his audience already knows. She puts it on so that Ares will not see her, she leans on the spear as Diomedes thrusts, and the bronze goes into the war god’s belly. Ares screams with the voice of nine or ten thousand men and leaves the field. Nobody on either side ever learns who really struck the blow.

The Greek name is plainer than the English ones. Kynee meant a cap of dog skin, the cheap hide headgear of a countryman or a foot soldier, and in time the word stretched to cover helmets of any material. So the grand Helm of Darkness of later retellings began as something closer to a leather hood. The other half of the name does more work. The Greeks themselves heard in Hades the sense of the unseen one, and a Roman-era handbook on the constellations spells the logic out, saying the helmet took its name from invisibility itself. Whether the cap belongs to the god or simply shares his nature is a question the name never had to answer.

The story of its making comes from the mythographer Apollodorus. When Zeus went to war with the Titans he needed allies, and he found them in the pit of Tartarus, where the Cyclopes had been locked away. He killed their jailer, the monster Campe, and let them out. They paid him back with a smith’s gratitude: thunder and lightning for Zeus, a trident for Poseidon, and for the third brother a helmet. Armed with all three, the gods won the war and divided the world. Three gifts, then, and two of them are loud. The thunderbolt splits the sky and the trident shakes the ground. The third simply removes its owner from the scene, which suits the brother who drew the kingdom nobody visits twice.

Here the record does something odd. No surviving story shows Hades wearing his own cap. It is always on somebody else’s head. Athena has it at Troy. Hermes has it in the battle against the Giants, where Apollodorus says he wore it to kill a giant called Hippolytus. And Perseus has it for the most famous errand of all.

Perseus came by it at third hand. Sent to fetch the Gorgon’s head, he was led by Hermes and Athena to the Graeae, the three grey sisters with one eye and one tooth between them. He snatched both in the instant they were being passed from hand to hand and held them hostage until the old women told him the way to certain nymphs. The nymphs kept what he needed: winged sandals, a wallet called the kibisis to carry the head, and the cap. Apollodorus is exact about what the cap did. With it on, Perseus saw whomever he wished to see, and nobody saw him. It did not darken the wearer’s eyes. It only erased him from everyone else’s.

It was not the cap that killed Medusa. Perseus managed that with a curved blade and a polished shield, watching her reflection so that he never met her gaze. The cap earned its keep a moment later. Medusa’s two sisters were immortal, and they woke. They rose from the rock with a noise of wings and brass and went after the killer, and they could not find him. He was already in the air with the head heavy in the wallet on his back, and the thing on his head had folded him into the dark. The old poem called the Shield of Heracles freezes that instant in metal: Perseus worked in gold, flying with his feet clear of the shield’s surface, the Gorgons close behind him, and on his head the terrible cap of Hades with the murk of night around it.

That phrase is as near as any ancient writer comes to describing the thing. It is a cap, it is made of hide, and it wears darkness the way other helmets wear a plume. Nothing is said of its colour, its weight or its shape. Painters and metalworkers, stuck with the job of drawing an object whose whole purpose is not to be seen, usually gave Perseus an ordinary traveller’s cap and sometimes added wings. Pausanias saw the handover itself on the bronze reliefs in Athena’s temple at Sparta, with the nymphs presenting the hero with cap and sandals. Even there, the cap is only a cap.

By the classical age it had slipped out of the stories and into conversation. Aristophanes gets a laugh out of it in the Acharnians, pointing at a poet whose hair was so thick, black and shaggy that a man could vanish under it. Plato sets it beside the ring of Gyges when he asks whether anyone would stay honest if nobody could ever catch him. Later lexicons record the phrase as a proverb for people who hide themselves by some device. The helmet of the lord of the dead had become a way of talking about shifty neighbours.

Its powers are narrow and complete. The cap hides its wearer from mortal eyes, from monsters with a gaze that kills, and from another god standing a spear’s length away, which is more than most divine disguises can claim. It leaves the wearer free to see, move and strike. It asks for no spell and no skill. Put it on and the world loses track of where its wearer is.

The limits are just as clear, and they follow from the same nature. The cap conceals and does nothing else. It turns no blade and blocks no stare, so Perseus still needed the shield, the sickle and a steady hand. It does not silence a footfall or lighten a body, as the creaking axle at Troy shows. And it is never anyone’s to keep. Athena has it for one afternoon. Perseus hands the cap, the sandals and the wallet to Hermes as soon as the work is done, and Hermes carries them back to the nymphs. A thing that makes its wearer disappear turns out to be very hard to hold on to, and after that return the stories lose sight of it too.

Frequently Asked Questions

What is the Cap of Hades?

The Cap of Hades is a magical cap or helmet in Greek mythology that makes its wearer invisible. Its Greek name, Aidos kynee, means the dog-skin cap of Hades, and it is also called the Helm of Hades or the Cap of Invisibility. The wearer of the Cap of Hades can still see everyone else.

Who made the Cap of Hades?

The Cyclopes made the Cap of Hades. According to Apollodorus, Zeus freed the Cyclopes from Tartarus during the war against the Titans, and in return they gave Zeus thunder and lightning, Poseidon a trident and Hades a helmet. The gods used these three gifts to defeat the Titans.

Who wore the Cap of Hades?

Athena, Hermes and Perseus all wore the Cap of Hades. Athena used it in the Iliad to hide from Ares while she helped Diomedes wound him, Hermes wore it to kill the giant Hippolytus, and Perseus wore it to escape Medusa’s sisters. No surviving story shows Hades himself wearing the cap.

How did Perseus get the Cap of Hades?

Perseus borrowed the Cap of Hades from a group of nymphs. He forced the Graeae to tell him where the nymphs lived by stealing the single eye and tooth the three sisters shared. The nymphs gave him the cap, winged sandals and a wallet called the kibisis, and after killing Medusa he returned all three through Hermes.

What can the Cap of Hades not do?

The Cap of Hades only hides its wearer. It does not protect against weapons or against Medusa’s gaze, which is why Perseus still needed a shield and a blade. It also does not hide weight or sound, since the chariot axle groaned under the invisible Athena at Troy.