Iris, the daughter of Thaumas and Electra, personified the rainbow, and was the special attendant and messenger of the queen of heaven, whose commands she executed with singular tact, intelligence, and swiftness.
Most primitive nations have regarded the rainbow as a bridge of communication between heaven and earth, and this is doubtless the reason why Iris, who represented that beautiful phenomenon of nature, should have been invested by the Greeks with the office of communicating between gods and men.
Iris is usually represented seated behind the chariot of Hera, ready to do the bidding of her royal mistress. She appears under the form of a slender maiden of great beauty, robed in an airy fabric of variegated hues, resembling mother-of-pearl; her sandals are bright as burnished silver, she has golden wings, and wherever she appears, a radiance of light, and a sweet odour, as of delicate spring flowers, pervades the air.
From: Berens, E.M. The Myths and Legends of Ancient Greece and Rome. New York: Maynard, Merril, & Co., 1880. Text in the public domain.