The subject of Head's painting is taken from Hesiod's Theogony, the earliest systematic account of the genealogy of the ancient Greek Gods. Iris was the goddess of the rainbow and the messenger of the Gods and the artist has depicted her carrying the waters of the underworld river, the Styx, to Olympus for the Gods to swear their most potent oaths by.
Head painted a number of versions of this subject, the first of which was completed in 1793 as his reception piece for the Academia di San Luca, at Rome, where he had settled in 1790. In 1800 Head exhibited what is presumably the largest version of the subject at the Royal Academy (no. 229) as a companion to Echo flying from Narcissus (no. 228), which was to be later engraved by Giovanni Folo.