The word that the ancient Greeks used for the rainbow and for the divine messenger who personified it was the same word: iris.
This is not a coincidence or a convenient mythological labeling. It is the linguistic fact that most directly expresses the Greek tradition’s understanding of what the rainbow was: not a natural phenomenon that happened to be associated with a divine figure as a symbol or an emblem, but a natural phenomenon that was the divine figure, whose appearance in the sky was the physical form that the divine presence took when it moved between the worlds. Iris was not a goddess who left rainbows in her wake as a side effect of her transit. Iris was the rainbow, and the rainbow was Iris, and the appearance of the arch in the sky after rain was the appearance of the deity moving between the human world and the divine one.
The linguistic identity of the rainbow and the goddess is the key to understanding what the Greek tradition was doing when it placed a divine figure at the center of the phenomenon: not anthropomorphizing an atmospheric event by projecting human form onto it, but recognizing the atmospheric event as itself divine. The rainbow did not need a goddess behind it to make it sacred. It was already sacred. The name Iris, applied to both the atmospheric arch and the divine figure, was the recognition of the sacred quality of the phenomenon in the most direct linguistic form available.
The same word also names the flower we call the iris, the part of the human eye that determines its color, and the colored membrane of the camera diaphragm: in each case the word iris is applied to something whose defining characteristic is a curved arc of color that creates or frames a visual effect. The linguistic history of the word traces the quality that the ancient Greek tradition identified as the rainbow’s essential character, the curved arch of distinct colors in graduated order, across the range of objects and phenomena that share that character.
The Genealogy and What It Encodes
Iris was the daughter of Thaumas and Electra, and the genealogy encodes the character of the phenomenon she personified in the Greek tradition’s characteristic manner of genealogical argument.
Thaumas, whose name derives from the Greek thaumazein, to wonder or to marvel, was one of the sea gods, a son of Pontus and Gaia: the sea as the source of wonder and astonishment, the quality of encounter with something so beyond the ordinary that the only response is the arrested attention of the wondering observer. Electra, whose name carries the root that gives the word electricity and the related phenomenon of amber’s static charge, was an Oceanid: one of the three thousand daughters of Oceanus and Tethys who embodied the world’s fresh waters, and whose name’s luminous quality connects her to the brightness and electrical charge that the stormy sky produced.
Iris born of Wonder and Brightness is the rainbow as the child of the two qualities that produce it in the experience of the observer who sees it: the wonder that the phenomenon itself generates, which is the suspended attention of the person who has looked up from whatever they were doing and cannot look away, and the brightness that the combination of sunlight and raindrops in the air produces when the geometry of the observation is exactly right.
Her sisters were the Harpies, Aello and Ocypete, whose names mean storm-wind and swift-flying and whose character is the violent and destructive dimension of the same atmospheric conditions that produce the rainbow: the storm that delivers the rain that makes the rainbow possible, in its violent form, was Iris’s sister, and the family relationship between the swift benign messenger and the swift destructive wind was the mythological encoding of the meteorological relationship between the rainbow and the storm.
The Homeric Iris
In the Iliad, Iris appears more frequently as a divine messenger than Hermes does, and her use in the epic reflects the character that her divine nature was understood to possess.
The Iliad’s Iris is primarily Hera’s messenger and Zeus’s messenger, and she is sent with instructions to recipients in the divine and the human worlds. She appears to Priam to instruct him to go to Achilles and ransom Hector’s body in Book XXIV, in the most emotionally concentrated use of the divine messenger function in the poem: the message she delivers, that the old king should enter the enemy camp alone to beg for his dead son’s body, is the message that initiates the Iliad’s resolution, the act of human vulnerability and courage that Achilles’ own grief makes him capable of receiving with compassion.
She appears to the winds Boreas and Zephyrus to ask them to come and blow on Patroclus’s funeral pyre, and they come: the goddess whose flight through the sky is itself the visible bridge between worlds is the appropriate divine emissary to the wind gods who live at the world’s edge, because her transit across the sky involves the same atmospheric medium that the winds travel through.
She appears to the Trojan women gathered at the assembly to warn them of the advancing Greeks, and she does so disguised as the mortal woman Polites: the rainbow that in ordinary circumstances announces divine presence takes, in this disguise, the form of a mortal figure, which is the mythological inversion that the Iliad uses for dramatic effect. The goddess whose normal appearance is celestial and unmistakable takes a human form when the message she delivers requires the appearance of ordinary human warning rather than divine revelation.
The speed that the tradition attributes to Iris, which Homer expresses through the comparisons of her transit to the movement of hailstorms and to the speed with which a line drops into the sea when a fisherman casts it, is the speed of light: the rainbow is visible at the moment when the alignment of the observer, the water droplets in the air, and the sun behind the observer is achieved, which is instantaneous, and the divine messenger who personifies the rainbow moves with the same instantaneous quality that the rainbow’s appearance has.
Iris and Hermes | The Two Messengers
The Greek divine administration maintained two messenger deities, and the distinction between them reflects the character of the two divine communication channels they represented.
Hermes was the messenger of the Olympian administration, the divine courier whose function was the management of the communications between the Olympian gods and the human world in its ordinary transactional dimension: the divine instructions that required delivery to mortal recipients, the divine decrees that needed to be communicated to individuals, the guidance that the gods provided to the heroes they favored in the situations those heroes encountered. Hermes moved through the world as a divine figure in human or near-human form, capable of disguise and of the ordinary social interaction that the delivery of messages in the human world required.
Iris’s communications were not transactional in the same way. She was sent by Hera and Zeus when the communication required the quality of the divine presence itself rather than the content of a message that could be delivered in words. The rainbow as a divine communication does not deliver a verbal message: it announces a divine presence, signals a divine attention, marks a moment as one in which the divine is actively involved in the human situation.
Hesiod, in the Theogony, gives Iris the function of carrying water from the Styx, the river of the underworld that was used in the most binding of divine oaths: when the gods swore an oath by the Styx, Iris was sent to fetch the water that the oath required, which placed her as the divine figure at the intersection of the celestial and the chthonic, the visible arch in the sky whose other end descended into the underworld’s most sacred river. The rainbow as visual phenomenon spans the visible sky from the earth at one end to the earth at the other, disappearing below the horizon at both ends: the myth that places Iris’s descent into the Styx is the mythological encoding of the observation that the rainbow’s ends touch the earth and disappear into it.
What the Rainbow Announced
The ancient Greek understanding of what the appearance of the rainbow meant in a situation was not a uniform positive omen that the appearance of Iris in the sky communicated. The heritage was more nuanced. The messages that Iris delivered in the mythological world were of varying content, and their character depended entirely on the divine authority who had sent her.
The rainbow as the visible form of a divine messenger was the announcement that something was about to be communicated between the divine world and the human world, and the content of that communication was not contained in the rainbow itself but in what followed it. The appearance of the rainbow was the signal to attend, to watch, to be ready to receive whatever the divine presence was about to deliver.
This is the quality that distinguishes the rainbow’s divine communication from the lightning bolt, the earthquake, and the other atmospheric phenomena that the Greek heritage associated with divine activity: the lightning bolt was itself the message, the direct expression of Zeus’s power and intention, requiring no interpretation. The rainbow was the precursor to the message, the announcement that the divine channel was open and that communication was about to take place.
The heritage that the rainbow was always a positive sign, always a symbol of divine benevolence and hope, is a simplification that the mythological heritage does not fully support. Iris was sent by Hera in the Iliad to deliver the instruction that Achilles should cease grieving and send Thetis to receive the instructions of Zeus, which was not a threatening message but was also not simply an announcement of divine favor. She was sent to warn Priam to ransom Hector’s body, which required the old king to enter the enemy camp in his grief and vulnerability. The rainbow announced the divine presence and the divine communication, and the divine communication was whatever the divine authority who sent it required, which was not always comfortable.
The Name’s Persistence
The word iris has survived in the living languages of the contemporary world in forms that preserve the visual character that the ancient Greek tradition identified as the rainbow’s essential quality: the curved arch of distinct colors organized in a graduated sequence.
The iris of the human eye is the colored ring that surrounds the pupil, the structure that determines eye color and controls the amount of light that enters the eye through the pupil’s dilation and contraction. The naming of this structure as an iris is the naming of the colored circular structure after the rainbow’s arc: the iris of the eye is the eye’s rainbow, the curved arch of color that frames the opening through which the eye receives light.
The iris flower, the genus whose approximately 300 species display the combination of the three outer falls and the three inner standards in a structure that creates the visual impression of the rainbow’s multiple distinct colors in a single bloom, was named for the same visual quality. The naming is Dioscorides’ in the first century CE, the Greek physician’s engagement with the plant in his De Materia Medica giving the genus the name that the visual resemblance to the rainbow’s color arrangement made appropriate.
The iris diaphragm of the camera and the microscope, the adjustable aperture whose overlapping blades create an opening of variable size by sliding across each other in the motion that produces the circular aperture at the center, was named for the iris of the human eye rather than for the rainbow directly, but the chain of naming is continuous: the camera’s iris is the camera’s eye, which is named for the human iris, which is named for the rainbow, which is Iris.
The visual quality that the ancient Greek tradition identified as the defining character of the rainbow, the curved arch of distinct colors organized in a sequence, has been recognized and named in each of these applications as the quality that connects them to the original phenomenon and to the deity who personified it. The word has traveled three millennia from the Homeric Iris of the Iliad through Dioscorides’ plant naming through the anatomist’s eye nomenclature to the photographer’s aperture, and in each case the word carries the same visual quality that made it the right word for the rainbow and the right name for the goddess who was the rainbow.
The Rainbow and the Rain
The meteorological accuracy of the ancient tradition’s understanding of what produced the rainbow was more sophisticated than the mythological framing might suggest.
Aristotle, in the Meteorologica, provided the first systematic ancient Greek account of the rainbow’s optical mechanism: the rainbow was produced by the reflection and refraction of sunlight by the water droplets in the air after rain, with the colors of the visible spectrum appearing in the order because of the angles at which different wavelengths of light were refracted by the water droplet. Aristotle’s account was not complete in the terms that the seventeenth century’s development of the physics of light would provide, but it was the correct identification of the phenomenon’s mechanism: sunlight, water droplets, and the geometry of the observer’s position relative to both.
The mythological heritage that preceded Aristotle’s physical account was not ignorant of the meteorological conditions that produced the rainbow. The ancient heritage consistently associated Iris with the atmospheric conditions in the aftermath of rain, with the clearing sky and the combination of remaining moisture in the air and returning sunlight that the rainbow required. The myth that the goddess’s appearance left the arch in the sky as the trace of her transit was the mythological encoding of the observation that the rainbow appeared in the atmospheric conditions that the myth associated with the goddess’s presence.
This was not a confusion of cause and effect. It was a different framework for understanding the same relationship: the meteorological conditions produced the rainbow, and the rainbow was Iris, and Iris was the divine presence whose movement between the worlds the rainbow announced. The frameworks were parallel rather than competing, and the transition from the mythological to the physical account was the transition between two different registers of the same observation rather than the replacement of false belief by true knowledge.
At Olympus Estate, Mythic Essays moves through the deeper currents of the Greek tradition. Iris was the rainbow, and the rainbow was Iris, and the word that named both is still the word for the colored ring of the human eye and for the aperture of the camera and for the flower with the three falls and the three standards. The rainbow did not need a goddess behind it to make it sacred. It was already sacred. The name was the recognition.
